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Posts about Density

Development


DC will probably never be too dense. These comments explain why, in a nutshell.

Some people think "density" means "a city that's packed to the gills." But a couple of our commenters recently pointed out that our region has more than ample space, and adding more housing isn't just necessary—it's beneficial.


This is 16th Street NW. Does it look to you like DC is out of space, with people packed in so tight they can't function? Yeah, me either. Image from Google Maps.

On election day, we re-ran a post from April Fools Day that satirized both the presidential election and the classic argument that neighborhoods are becoming too full and thus shouldn't get more residents or housing.

In his Onion-esque post, David Alpert wrote about how low-density the property at 1600 Pennsylvania Avenue NW is, and how essentially building pop-ups onto the White House would mean making room for lots of new residents, from Hillary Clinton and Bernie Sanders to Donald Trump and Ted Cruz.

One commenter, Rick, got the point and disagreed with it:

Why do some people want to populate DC as densely as humanly possible? To be honest, I liked it better 15 years ago when there were a couple hundred thousand fewer people living here.
It's worth saying that the viewpoint expressed here is not irrational, nor does it make the person saying it a bad person. A lot of people like DC because it's not as dense as some of the country's other big cities, and they're allowed to feel that way. The issue is that it's not accurate to say that adding more dense housing, which the region does need to do, would mean that living here would become completely untenable.

One reply to the above comment, from a commenter named alurin, made this point—essentially, that "There is no such thing as a city that has run out of room"—quite well:

I don't think anyone wants DC to be "as dense as humanly possible". Wikipedia lists DC's current population density as 11,011 people per square mile. That puts us outside of the top 100 densest cities in the US, much less the world. If we doubled the population of the district, density would rise to 22K/sq mile, approximately equivalent to Somerville, MA, a very pleasant city where I lived for several years.

The densest city in the world is Manila, Philippines, with a density of 107k/sq mile. We would have to squeeze about 6.5 million people into the district to reach that benchmark. So let's cut out the hyperbole.

Many people want the city to get somewhat denser because a lot of people want to live here. The bigger the gap between housing supply (proportional to density) and demand to live here, the more excruciatingly expensive it will get to live here.

Two other responses that popped up made additional good points beyond that fact that "density" doesn't mean "make this place the most dense it can possibly be." Making room for more people is simply part of the equation if you want to thrive economically. And when you do that, you reap social and cultural benefits.

One came from Republic:

People don't cease to exist just because we want them to. The whole country's population is growing and needs to be housed. Opposing density doesn't make sense unless we somehow stop population growth.
And one came from Dan:
There is demand for housing within the District. Pick your favorite "DC is great" reason--walkable, transit-oriented, culturally rich, etc. If those moving in are bigger contributors to the tax base than they are users of city services (single, healthy, childless, productive), then why not welcome them with open arms?
I don't believe anyone wants to make DC "as dense as humanly possible."
DC already has a wide variety of neighborhoods that accommodate a variety of people at different densities, none of which are unbearably overcrowded. Adding more people won't change that.

Politics


America's most unattainable housing is right by downtown DC. That's a huge problem.

Tuesday is Election Day! In celebration, we're re-running our favorite April Fools post from earlier this year to remind everyone exactly how important it is to go vote! The polls are open until 7:00 in Virginia, and 8:00 in the District and Maryland. Find your polling place here, and Greater Greater Washington's endorsements here. Don't forget to vote!

Five people are currently vying for the chance to occupy the White House this November, but only one will win. This is a classic supply and demand problem, and the solution is simple: Build more housing.


Concept rendering for The Estates At President's Park. Original image by Jeff Prouse.

1600 Pennsylvania Avenue, NW is an extremely low-density property, with 82 acres housing a population of only 5 people (and a very small amount of office space). Even without adding new buildings, the existing one could become a taller apartment building with plenty of room for the Clintons, Sanderses, Trumps, Cruzes, and Kasichs, even without changes to Washington, DC's federal height limit.

This building is also located in a gated community with large open spaces around it which serve little purpose. They are off-limits to most pedestrian foot traffic and residents of the exclusive community are rarely seen using them either. The Ellipse, just to the south, is largely used as a parking lot. Developing some of these open areas could have provided even more housing.


Significant underutilized land. Photo by US Department of Defense via Wikimedia.

The exclusionary nature of this area has already prevented numerous families from being able to move here. According to news reports, families from Florida, New Jersey, Maryland, Kentucky, Arkansas, California, Pennsylvania, Virginia, Texas, Wisconsin, Louisiana, Rhode Island, South Carolina, and others gave up on their hopes of being able to move here for a better job. The lack of available housing is an clear impediment to labor mobility.

Historic preservationists and other groups may complain about such a move. After all, this house is one of many which tour groups frequently pass by on their tours, and some (but not all) US Presidents lived here, adding to its historic value.

However, Washington has many historic buildings; this one is not as architecturally interesting as the office building next door to the west. The National Park Service, which controls the area, is so under-funded it may have to shut down a bridge which carries 68,000 vehicles a day. NPS needs to prioritize its funds and not waste so much money on a property which few people can enjoy.

Original architect James Hoban actually proposed a larger building, but changed his initial design, supposedly to better reflect the "monumental" nature of Washington, DC. As Kriston Capps put it, it's a "Hoban cut off at the hipbone." "It's a perfect architectural metaphor for the almost-urbanism that characterizes life in Washington," he wrote.

Candidates react to the idea

Reached on his corporate jet, Donald Trump said, "I think it's terrific. I can make a great deal to build this and I'm working with the GSA on the hotel down the street which will open early and will be the best hotel in all of DC. I'm good at building things. I'm the best. I have built so many things. Good things, you know, really good things. I know how to build. I have the skills, the best skills. And I can get this done. And I have great taste in furniture, the best taste. We'll increase the quality of the finishes substantially, marble finishes, very, very high quality of luxury marble, the most luxurious marble you've ever seen. Just phenomenal luxury."

Based on the District's inclusionary zoning ordinance, the new White House will be required to include one affordable dwelling unit, which will likely go to Marco Rubio.

In a press release, Hillary Clinton's campaign manager said they'd worked out an agreement to use the basement to build an ultra-secure server room inaccessible to the House of Representatives.

Reached on the campaign trail in Wisconsin, Ted Cruz expressed his opposition to the proposal. "I'm an outsider. I don't need a building to live inside."

The Burlington, Vermont headquarters of Bernie Sanders' campaign sent this statement: "This is why we need to break up the big banks and make sure everyday Americans benefit instead of just Wall Street and big corporations."

While many are excited about the 1600 Penn project's increased density, others have expressed concern that this is simply another situation where developers will trigger displacement of another black family from a neighborhood with an overwhelming percentage of African-American residents according to the 2010 Census.

Still, this neighborhood is very close to ample parks, stores, jobs, and transportation, including multiple Metro stations. The low quantity of housing is a clear public policy failure. Let's end the Lafayette Square housing crisis immediately.

Zoning


This map illustrates DC's new zoning rules

Zoning is the legal framework that shapes just what can be built where in most cities, and DC just enacted a new zoning code. It's pretty detailed, but we're in luck: the the District's Office of Zoning made this interactive map to illustrate where different zones are, what they mean, and why they're organized it that way.


Click to explore DC's new zoning map, including its quick descriptions of each zone.

The map is one of many the zoning office has published to explain the changeover. If you click the image above, you'll see a sidebar that shows the eight categories that define how land in DC can be used: Residential; Residential Flat; Residential Apartment; Neighborhood Mixed Use; Mixed Use; Downtown; Production, Distribution and Repair; and Special Purpose.

Clicking on the individual colored areas will bring up will bring up the specific "zone district," one of the three parts of zoning that regulate the use and shape of a building. The others are the rules that apply everywhere in the city and processes that give the regulations flexibility, like Planned Unit Developments. But zone districts are the rules that shape specific neighborhoods, and it's usually what people are talking about when they mention zoning.


Residential Flat (RF) is one of three types of Residential zones. Below, you can see examples of the others. Photo from DC's Office of Zoning.

By breaking down the official map into the big categories and color coding them, you can see patterns. For example, the yellow and orange shapes show areas where only houses, flats, or apartment buildings can be built. At a glance, over half of DC's residential land is zoned exclusively for detached single-family housesthat's conservative, since most other zones also allow single-family houses.

Image from DC's Office of Zoning.

The new code organizes zone districts for residential use by building type: single family houses (R), flats in small apartment buildings and subdivided rowhouses (RF), and large apartment buildings (RA).


Residential Apartment (RA). Photo from DC's Office of Zoning.


Residential (R). Photo from DC's Office of Zoning.

Zooming in on Historic Anacostia, the map below shows the denser RA and RF areas closer to Martin Luther King, Jr. Ave. SE, with the area uphill restricted to townhouse, duplex or detached houses by their R-3 zone designation.

It might also look like there's a lot of land across the city that's zoned RA. But looking closer, a lot of this land is for campuses like those of American University, the Armed Forces Retirement Home, or built out with low-rise garden apartments in areas like McLean Gardens and Congress Heights.

Commercial zones saw a bigger change

The new code has no purely commercial zones. The downtown zone districts (D), meant for the dense core at the center of the city, don't exclude apartments. Some even incentivize residential buildings by letting apartments be denser.


Downtown (D). Photo from DC's Office of Zoning.

Farther out, medium-density commercial areas are now called Mixed Use (MU), to reflect that the code encourages both commercial and residential in those areas. That's not new, but the name of old districts like "C-2-A" suggested otherwise.


Mixed Use (MU). Photo from DC's Office of Zoning.

A good example can be found around Mount Vernon Triangle and Northwest One: it's mostly zoned D and MU, and many of the new residences built there are not in residential zone districts.

H Street NE was one of several areas used to have "overlays" added to modify the standard zone districts in a geographic area. Sometimes those modifications were the same across commercial and residential properties, but often they laid out custom rules for every single zone district the overlay touched. To figure out what was allowed on a given property, you'd first look in one chapter of the code for the "base zoning," then flip to another chapter for the overlay.


H Street's old zoning.

Now, each of the existing combination of zones has been given its own subsection. Small commercial strips like H Street fall into distinct moderate-density neighborhood mixed use (NC) zones, meant to create a special character for individual neighborhood main streets, like Georgia Avenue and Carroll Street in Takoma.


Neighborhood Mixed Use (NC). Photo from DC's Office of Zoning.

Now, the overlay and base zoning information is all in one place, from the statement of purpose to technical restrictions. The same is true for the Special Purpose customized zones, used meant to give big areas like Uptown Arts on U and 14th Streets (ARTS), or at Walter Reed (WR) unique characteristics.


H Street's zoning under the new code.

Zoom in on the map and click on a parcel, and the map will show a quick description of the site's zoning. This little chunk of Howard University's campus is one of the few remaining industrial (PDR, short for Production Distribution & Repair) zones in DC's northwest quadrant.


Production, Distribution and Repair (PDR). Photo from DC's Office of Planning.

None of these have industrial uses anymore; this lots is a development called Wonder Plaza, with fast-food eateries and no heavy machinery.

Perhaps this PDR designation was just kept by inertia; I'm not sure I would have noticed that without this map.

For me, the new organization of the code and the Office of Zoning's map help with understanding not only what someone could build on some plot of land, but also how earlier planners shaped the the city and what might need to change. What does this map help you see?

Correction: An earlier version of this post said that over half of DC's residential land is zoned exclusively for detached single-family houses. That isn't the case; over half the land is zoned exclusively for single-family houses, but not detached single-family houses.

Transit


We know where most of DC's population lives. Does Metro run through those places?

The maps below show where DC's most densely-populated pockets are, as well as where its Metro stops are. It turns out they aren't always the same places, or in other words, DC isn't building enough around transit.


Highest density census tracts comprising 50% of DC population, with Metrorail overlay. Map by John Ricco, overlay by Peter Dovak.

Back in July, John Ricco created a pair of maps showing that 50% of DC's residents live on 20% of the land, and a quarter of the population lives on just 7% of the land. Peter Dovak, another Greater Greater Washington contributor, did me the favor of overlaying John's maps onto the Metro system.

Looking at the map above, which shows where 50% of the population lives, there are some obvious areas of overlap between density and Metrorail access, including the Green/Yellow corridor through Shaw, Columbia Heights, and Petworth. The southern area of Capitol Hill also has multiple Metro stops and is relatively dense.

But what stands out are the dense places that aren't near Metro. The northern end of Capitol Hill, including the H Street corridor and Carver Langston, as well as the areas to the west around Glover Park, a few tracts to the north near Brightwood, and two larger areas east and west of the Green Line in Ward 8, near Congress Heights and Fort Stanton Park.

All of these places show that DC's growth isn't being concentrated around its transit (its transit isn't being extended to serve dense areas either, but that's harder to do).

Of course, Metro is far from the only way to get around. Residents of high density, Metro-inaccessible neighborhoods rely on buses and other modes to get where they need to go; specific to northern Capitol Hill, for example, there's also the DC Streetcar). Also, some areas next to Metro stops are low density due to zoning that restricts density or land nobody can build on, like federal land, rivers, and parks.

Still, it's useful to look at where DC's high-density neighborhoods and its high-density transit modes don't overlap, and to understand why.

25% of DC's population lives close to metro... mostly

Really, the S-shaped routing of the Green Line is the only part of Metro in DC that runs through a super dense area for multiple stops.

Looking at the map that shows 25% of the District's population, the Green/Yellow corridor helps make up the 7% of land where people live. But so does Glover Park, Carver Langston, and a tract in Anacostia Washington Highlands near the Maryland border—and these places are a long way from a Metro stop.


Highest density census tracts comprising 25% of DC population, with Metrorail overlay.

There are historical reasons for why things are this way

According to Zachary Schrag in The Great Society Subway: A History of the Washington Metro, Metro wasn't meant to be an urban subway; it was always meant to be a regional rail system. It explicitly bypassed the relatively few people in DC's high-density areas, in favor of speeding up rides for the greater number of through-commuters. Apparently, DC had little say in that decision, which is evident in the map.

On the other hand, the citywide streetcar plan was meant to bring rail access to many more DC residents—partly because, well, it was to be built by DC's government, for DC's residents, which Metro was not.

The first version of this post said that a tract was in Anacostia, but it's actually in Washington Highlands.

Development


Adams Morgan could get more housing and preserve its plaza, too. But it probably won't.

Some Adams Morgan leaders have said "no" once again to a proposal to replace an ugly 1970s bank building at the corner of 18th and Columbia. Redevelopment would destroy what's now a plaza, but does it have to? If neighbors got over some "height-itis," maybe not.


April 2016 rendering by PN Hoffman.

For most of this year, controversy has swirled around proposals from PN Hoffman to redevelop what's now a two-story SunTrust bank building dating to 1973 and a brick plaza. Hoffman's initial proposal left a much smaller (but more attractively landscaped) plaza at the corner. Opposition was immediate, and took two forms.

Some people, like the "Save Our Plaza" group, focused most on the plaza itself. The place has some history involving the neighborhood's past efforts to push for fair lending to low-income homebuyers from the Perpetual Federal Savings bank, which used to use the building. Others simply feel that an open gathering space at Adams Morgan's central corner is a worthwhile part of the urban environment.


The plaza. Photo by nevermindtheend on Flickr.

Others, like Advisory Neighborhood Commission 1A zoning committee chair JonMarc Buffa, focus opposition mostly on the size of the proposed building. Much of the 18th Street strip is three stories high, while this building would have been six or seven to the cornice line (plus a set back penthouse).

There are buildings of similar height in the immediate area, but many people including HPRB member, architect, and stalwart opponent of height (except on his own buildings) Graham Davidson said it was too tall and too massive.


September 2016 rendering by PN Hoffman.

Many others, like the commenters on this Borderstan article, argue that Adams Morgan could benefit from more residents (helping neighborhood retail besides bars and late-night pizza places thrive), that DC needs housing, and besides, this is private property.


Open space isn't a bad thing, but neither are buildings. Photo by NCinDC on Flickr.

How about a plaza AND new housing?

While this is indeed private property (though the city's historic preservation process has wide latitude to control what's built), there's some merit to the argument that in a well-planned Adams Morgan, it would still be good to have a plaza here.

My neighborhood has a large circular park right at the Metro station. Even though it takes a lot of land away from being used for needed housing, it's a terrific amenity and I wouldn't want it developed.

However, that doesn't mean I want to keep people out of the neighborhood, either. I support building more housing on other sites and would support taller buildings around the circle where they are low.

What is the priority for Adams Morgan residents? If the plaza is the most important thing, they could propose that instead of shrinking the building, PN Hoffman makes it even taller, but in exchange leaves more of the site open. Or want to minimize height? Then the plaza, which is not public land, probably has to go.

Site plan showing the current building.

I'd go with more height and more plaza space if possible. Tall buildings at prominent corners are actually a defining feature of DC (to the extent any DC building is "tall") and other cities. This marquee corner would be a great spot for something really dramatic that could anchor and characterize Adams Morgan. All of the proposals were architecturally conservative, and have gotten even more so in subsequent revisions. This is why DC has a reputation for boring architecture.

The best vehicle for such an arrangement would be what's called a Planned Unit Development. It's a more involved process that gives a developer more zoning latitude in exchange for benefits to a community. Hoffman hadn't been pursuing a PUD, perhaps hoping for a quicker turnaround in the process, but if neighbors agreed to support something with more density and more plaza space, it would reduce the uncertainty of doing a PUD and open up possibilities for a better project.

I don't want to represent that something is possible that might not be: I haven't talked to PN Hoffman about this possibility. Making a building taller adds construction cost; I'm not privy to the dynamics of their deal to control the land. But in most projects, there is some opportunity for give and take if neighbors really were willing to prioritize asking for one thing and being more flexible on another.


Not a lot of activity. Photo by AgnosticPreachersKid on Wikimedia Commons, CC BY-SA 3.0.

And let's not kid ourselves—this plaza is nothing special. It's hosted a farmer's market, but Hoffman has said they'd work to relocate it to another large expanse of sidewalk right across the intersection. For most people walking through Adams Morgan, this spot is just the ugly dead zone in between the interesting commercial strips in various directions.

A smaller but well-designed plaza could be more useful. A larger AND well-designed one could be even better, and potentially even feasible if height weren't such a bugaboo.

Unfortunately, area activists don't seem likely to suggest a taller building and a better plaza. Instead, the Save Our Plaza people seem almost as angry about the number of feet proposed for the building; their petition actually mentions the height first, before the plaza.

A more detailed plan could help

The DC Office of Planning created a vision plan for the neighborhood last year, and it in fact cites the plaza as something to hopefully preserve. But there was no official policy change to protect it, nor did that plan consider offsetting zoning changes to add more housing elsewhere in the neighborhood. The plan had good uncontroversial ideas (better wayfinding, more green roofs, public art) but doesn't actually determine where new housing can go.

The zoning for this site allows a building atop the plaza. Historic preservation is almost wholly discretionary and the preservation board doesn't publish detailed written decisions, making it impossible to know what is and isn't acceptable.

If DC's practice was to devise more concrete plans, we could imagine having a clear vision that lays out how much housing DC needs, what proportion of that would be fair to allocate to Adams Morgan, and a strategy for where to put it and where not to. The zoning could then match this vision instead of bearing at best a passing resemblance.

Instead, it seems that the only thing that would satisfy Advisory Neighborhood Commission 1C is virtually no change at all. That's not reasonable; the city is growing, and so should Adams Morgan's core. But neighborhood leaders can think through how they'd best accommodate that change, and the government could help. And maybe this site could still have a better building and a plaza at the same time.

Development


Houston took this winning approach to adding housing. Could DC do the same?

Though DC has been adding lots of housing, new development is concentrated in large, expensive buildings in neighborhoods that are running out of empty lots to build on. Houston's approach to densification—replacing detached single family homes with townhouses—offers some important lessons for DC's long-term growth.


This type of infill is illegal in DC's low-density neighborhoods. All images from Google Maps.

DC set a record last year when it permitted nearly 5,000 new housing units, the most ever in recorded history. Looking at the breakdown of new units permitted, we see a striking pattern: almost all new housing is in large multifamily apartment buildings.


Chart by the author.

Because high-rises cost more to build than smaller buildings, they come with high price tags once completed. That means that new construction in DC is concentrated at the luxury end of the market, which is far too expensive for most households to afford.

All this new housing is geographically concentrated, too. Neighborhoods like Navy Yard and Southwest Waterfront have added the lion's share of DC's new housingplaces where there are many open lots to build on and few neighbors to complain. Meanwhile, DC's single family residential neighborhoods have largely avoided change.

While this has been an effective strategy in the last few years, it can't continue forever. There are only so many liberally-zoned former industrial sites and parking lots that we can build on. If DC is to continue to grow, areas that contain primarily single family homes will need to densify.

The Houston approach

Houston is famous for its car-oriented sprawl. Though it lacks a zoning code, the city has historically mandated low-density development through non-zoning regulations, like minimum lot sizes and stringent parking requirements.

But in 1999, Houston enacted sweeping land-use reforms: it decreased the minimum residential lot size from 5,000 square feet to 1,400 in close-in neighborhoods. In effect, this reform legalized townhouses in areas with suburban-style houses on huge lots. Two or three houses could now take the spot of one.

The political significance of these reforms cannot be overstated. Single family zoning is somewhat of a third rail in American local politics; it's exceptionally rare for residents of suburban-style neighborhoods to allow denser development. Urbanist commentators have noted that "missing middle" housingforms like duplexes and small multifamily apartments—has been regulated away in most American cities. Houston represents an important dissent from the notion that single family neighborhoods are to be preserved at all costs.

The results of these reforms have been remarkable. Areas that were once made up entirely of ranch-style houses, McMansions, and underused lots are now covered in townhouses:


The Rice Military neighborhood.


Shady Acres.

The infill process is typically incremental, with detached homes being replaced one at a time. This often leads to a diversity of housing styles on a single block:

Other blocks are unrecognizable in their transformation:

And in some parts of the city, this redevelopment process has gone hand-in-hand with light rail expansion:

(There are so many striking before-and-after images that I programmed a twitter bot, @densifyingHOU, that tweets one out every day.)

One major benefit of these townhouses: they're cheap! Development at this scale uses cheaper construction methods than those of large buildings, and Houston's straightforward permitting process reduces regulatory uncertainty and thus financing costs. A cursory search on real estate websites reveals luxury townhouses a mile from downtown from the low $300s.

Now, Houston's approach does have its flaws. Parking is still mandated, setback requirements and inward-facing homes make for a lousy pedestrian experience, and some new houses are, frankly, ugly. In some areas, unhappy homeowners have lobbied successfully for block-level regulations that re-outlaw townhouses.

But the key insight here is that piecemeal densification is possible, and it works. Houston has found a way to add significant amounts of housing without sprawling.

Planners in cities like DC should take note: the status quo, where we protect the low-density character of leafy neighborhoods and funnel development into a small portion of the city, needs a thorough rethinking.

History


An alien notion: 800,000 DC residents

Over 800,000 people lived within the boundaries of the District of Columbia back in 1950. How did all of these people fit, with fewer and smaller buildings than today?


Photo by Jesse Means on Flickr.

The 1951 sci-fi classic "The Day the Earth Stood Still" inadvertently shows us how. Klaatu, a level-headed extra-terrestrial emissary, escapes captivity at Walter Reed Army Medical Center. He wanders down Georgia Avenue, away from not-yet-nuclear-weapon-free Takoma Park, and attempts to disappear into everyday DC.

To do so, Klaatu checks into a boarding house at 14th and Harvard in Columbia Heights. Each room houses one or two people, and as such there's scant privacy to be had: everyone overhears everything.

This is convenient for Klaatu, who knows little of Earthlings' simple ways, but probably annoying for the Earthlings. Conditions like these were common in DC homes at the time.

The 1950 census found 14.1% of the District's 224,142 occupied housing units to be "overcrowded" (with over 1 person per room). By 2011, that figure had fallen by 2/3, to 4.7%, similar to the 5.3% of homes in 1950 that were extremely overcrowded (more than 1.5 occupants per room).

This crowding meant that on average, every apartment and house in DC had one more person living inside: households were 50.2% larger! In 1950, 3.2 people occupied each dwelling unit. In 2007-2011, the number of persons per household had fallen to 2.13, so the city's population still fell to 617,996. That decline would have been much steeper had the city not built 74,760 new housing units: the city's population would have plunged to 477,422, and the nation's capital would be less populous than Fresno.

Household size shrank nationwide as families changed. In 1960, married couples with children outnumbered single-person households almost three to one. In 2010, singles easily outnumbered nuclear families nationwide, and by 5.57 to one in DC.

As DC gets reacquainted with the notion of population growth and begins to plan for a much larger population within the same boundaries, we'll have to have a realistic conversation about household sizes and housing production. A change of just 0.09 persons per household means the difference between planning for 103,860 or 140,515 additional housing units,1 or a total of 35% to 47% more units.

That amounts to 2,000-3,000 additional units per square mile of land, after subtracting the 10.5 square miles of parks and seven square miles of water from DC's 68 square miles.

Klaatu, unfamiliar with our contentious Earth politics and "impatient with stupidity," might propose to build a platform of 5-unit-per-acre suburbia above the existing city, or require every second or third home to be subdivided, or return to 1950s household sizes and require every home to take in one boarder (not necessarily extra-terrestrials). But since Klaatu is no longer with us, we will instead have to figure out more complicated ways of infilling a built-up city.

We've obviously figured it out before; after all, DC has added an Alexandria's worth of housing units to its existing housing stock since 1950, plus plenty of offices, museums, hospitals, parking garages, and the like.


1615 M Street. Image from Google Maps.
A lot of that change has happened around places like 1615 M Street NW, the address where a 1954 radio version of "The Day the Earth Stood Still" placed Klaatu's boarding house. Today, 1615 M is a 9-story Class A office building that brackets the historic Magruder and Sumner schools.

The area above K but below Massachusetts was a high-density mixed residential area in the 1950s, what Park & Burgess would've known as "the zone in transition," but today the height-constrained central business district has spread north to Massachusetts Avenue. Yet in fact many foreign visitors still board on that block, at the Jefferson Hotel and the University of California's Washington Center.

Unlike in the movie, there is no way that Klaatu can make DC's growth "Stand Still," and so the built fabric of many other DC neighborhoods will have to change in the near future. Thankfully, neither is there a grumpy Gort (pictured above) parked on the Ellipse, who will destroy the earth with laser-beam eyes if we don't all just get along.

We first ran this post in 2013, but since the history and ideas haven't changed, we decided to re-run it.

1 Based on this 2006 Urban Institute/Fannie Mae Foundation report by Margery Austin Turner forecasting 100,000 new residents, a target that the Sustainable DC Plan recently raised to 250,000.

Development


What do 80,000 people in a square mile look like? Depends on where you put them.

When we talk about dense housing, many think of New York City skyscrapers, or Soviet blocks. But as images maps of different neighborhoods in DC show, not all density looks the same.


A high-density block in Columbia Heights. All images from Google Maps.

Google Maps recently unveiled its auto-generated 3D imagery for DC. Using this feature, I compiled snapshots of what different levels of density—measured by people per square mile (ppsm)—look like throughout DC and Arlington. The population density numbers come from the 2014 American Community Survey, and I calculated at the census block group level.

5,000 people per square mile

In the Palisades, winding streets are lined with large houses (~5,000 ppsm):

And in Brookland, detached single family homes sit on lots with front setbacks and spacious backyards (~6,000 ppsm):

15,000 people per square mile

Though walkable, most of Georgetown isn't particularly dense, with blocks of tiny rowhouses clocking in at about 15,000 ppsm:

Lamond-Riggs achieves a similar population density with suburban-style duplexes (~13,000 ppsm):

20,000 - 30,000 people per square mile

With a mix of both historic and new-construction rowhouses, this block group in Hill East sits at around 22,000 ppsm:

This section of Fort Dupont is similarly dense, but looks much different. Garden apartments centered around green space and surface parking give this area a density of roughly 27,000 ppsm:

30,000 - 40,000 people per square mile

In Glover Park, rows of attached houses line a network of relatively narrow streets (~31,000 ppsm):

A mix of duplexes and garden apartments puts this part of Shipley Terrace at about 35,000 ppsm:

40,000 - 50,000 people per square mile

These blocks bordering the south end of Adams Morgan are almost entirely filled with large rowhouses, with a few bigger apartment buildings situated on the main thoroughfares (~45,000 ppsm):

In Rosslyn, parking lots and highways surround these 7- to 10-story apartment buildings (~47,000 ppsm):

50,000 - 60,000 people per square mile

These apartment complexes on Massachusetts Avenue near American University don't cover a lot of land area, but their height makes them relatively dense (~53,000 ppsm):

Dupont Circle's streets blend rowhouses with 4- to 8-story prewar apartment buildings (~55,000 ppsm):

80,000+ people per square mile

This section of Columbia Heights is mostly close-together 4-story apartment buildings, giving it both a high density and a human scale (~80,000 ppsm):

At the north end of Mount Pleasant, a large apartment complex pushes this block over 85,000 ppsm:

Just south of Logan Circle, bulky apartment buildings both old and new give rise to densities over 100,000 ppsm:

Development


50% of DC residents live on only 20% of the land

Also, a quarter lives on just 7% of it. I made these maps to illustrate that.


Maps produced by the author. Data comes from 2014 ACS five-year estimates.

According to survey data from the Census Bureau, 50% of DC's population lives on just under 19% of its total area (bodies of water are included). In absolute terms, that's almost 315,000 people living on roughly 8,000 acres.

Zooming in even more, we see that 25% of people living in DC inhabit just 7% of its land. These residents are mostly clustered around neighborhoods like Logan Circle and Columbia Heights, where housing is dense and transit is plentiful.

For comparison, 50% of New York City's population lives on only 11% of its land area:

Do you notice anything interesting in these maps?

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