Maps & GIS

The Figure-Ground of Race in Washington, DC

This map shows building footprints of Washington, DC, Arlington, VA, and Alexandria, VA, which together cover what used to be the ten miles square of the original District of Columbia. Each census block is colored in by its predominant race. Some of the gray areas are unpopulated office or landmark buildings that you’ll likely recognize, like the Pentagon.

I think of it as a new twist on race dot maps (popularized by Bill Rankin) that are constrained to the actual buildings people might live in. The physical separations of neighborhoods, set by rivers and highways and railroads, show as gaps, along with more subtle divisions: where city grids and blocks  give way to meandering suburbs.

The flaw with this map is that it shows dominance over diversity. Farther out in the suburbs racial neighborhood divisions are less sharp.

For this map I used QGIS, and blended a layer of census blocks colored by race onto publicly available building footprint shapefiles from local governments, a relatively new feature. This was much faster than running a spatial join to create a new shapefile of buildings assigned by block.

Open Data Portals – AlexandriaArlingtonDistrict of Columbia

Southwest Virginia: The Fall of Warner Country

Virginia Senator Mark Warner (D) is the face of a dying breed — the Democrat who could win Southwest Virginia.

Last Tuesday, former Republican National Committee chair Ed Gillespie was unable to take the Senate seat from Warner, but Gillespie was able to wipe out Warner Country.

The signs have been there for over two decades.


The course of partisan realignment in Virginia’s last 20 years could be charted through the electoral fortunes of Mark Warner, a Northern Virginia cell phone millionaire that could draw support among working-class whites. In his first Senate race in 1996 against incumbent Senator John Warner (the year of “Mark Not John” bumper stickers), Mark Warner outperformed in rural areas but met his end in vote-rich Fairfax County near Washington, DC, where he lost by over 50,000 votes.

Southwest Virginia’s New Deal coalition was still holding together at the close of the 20th century. Where Democrats relied on rural black voters to narrow the margins in rural areas east of Appalachia, the Scots-Irish of Southwest Virginia celebrated by Senator Jim Webb predominated in the mountains. Every single Democratic candidate for President between 1932 and 2004, with the exception of George McGovern, carried coal-rich Buchanan County, with the help of organized labor. But as the older generation, still loyal to the party of FDR and LBJ, began to pass away, fewer and fewer of their offspring chose to stay in Southwest Virginia, and those that remained did not inherit their partisanship.

In 2001, Mark Warner ran for Governor, airing a minute-long bluegrass campaign jingle imploring the “people of the mountains at the end of their rope” to “vote in this election to keep our children home”.

Mark Warner, the hero of the hills…
Warner won handily in 2001 with a coalition of black voters, middle-class suburbanites, and Southwest Virginia, but the cracks of the New Deal coalition in Southwest Virginia were already showing at other levels. Republicans had taken control of the Virginia House of Delegates in 1999, which allowed them to draw new lines for the 2001 elections. That year, Democrats lost 4 seats from the region in the Virginia House of Delegates — 1 to population loss through redistricting, and 3 to Republican replacements. This was only an intermediate stop in a long, slow decline for Democrats from Roanoke and Martinsville on west.

In 1992, Democrats held 14 of 16 Southwest Virginia seats in the House of Delegates. Today, they hold only 1 of 13, with Delegate Sam Rasoul of Roanoke holding onto the last seat, and a total of three seats gone to the winds of redistricting, pulled out by explosive population growth in the Northern Virginia suburbs, and pushed out by sluggish growth and decline in Southwest. With local offices serving as the bench for the Democratic team, an increasingly urban party is reliant on increasingly urban recruits.


One seat, the 4th District, is currently vacant, as Delegate Ben Chafin was promoted to the State Senate, replacing State Sen. Phil Puckett (last seen under investigation for possibly trading a resignation for a job and daughter’s judgeship, a scandal that Mark Warner managed to get entangled in).

Sam Rasoul is not the only one who could begin their bio with “The last Democrat in Southwest Virginia” in their chamber. State Sen. John Edwards is now the last Democrat in Virginia’s upper chamber from the region.

Virginia’s political future has long featured sharp differences between presidential years and off years. As rural strongholds of the FDR coalition are lost, Virginia Democrats are now almost exclusively reliant on strong minority turnout and fickle suburbanities. This strategy of running up the score in urban areas has kept Democrats in control of all 5 statewide offices (Governor, Lieutenant Governor, Attorney General, and both Senate seats) but leads to a structural disadvantage in downticket legislative elections. Thanks to this divide, Virginia can be considered a Democratic-leaning state in Presidential elections, with hollow success downticket.

Inefficiently packed in majority-minority and urban districts that are 60% or 70% Democratic, Democrats are forced to rely on increasingly difficult rural seats. Where you win doesn’t matter in statewide races, but it can tip the balance in single-member district legislatures.

Mark Warner was the last Democratic recruit of his kind, a Northern Virginian who could win big in Southwest Virginia. For Virginia Democrats, the future is bright for urban-based Democratic recruits who can run up the score in urban areas on the way to statewide victory. But as all victories in politics do, it comes with a tradeoff: as voters become better sorted in parties, Democrats in the countryside face increasingly long odds.

MAP: A Republican in Arlington, Once Upon a Time

Veteran Rep. Frank Wolf (R) announced this morning that he was declining to seek re-election. First elected in 1980 after unseating a Democrat, his district, once based in Arlington and inner Fairfax Counties in Virginia and stretching out to then rural Loudoun County, his district marched steadily westward, fleeing the increasingly Democratic inner suburbs. A Republican representing Arlington in Congress–a completely unthinkable scenario now in a county that lacks a single Republican elected official on any level

Below is a quick map I prepared comparing his first 1980 district with his now second to last district in 2013. The purple area contains overlap, the red area parts of the district lost since the 80s, and the blue area gained since then, using this excellent trove of historical boundary data from UCLA.



Here is the same map, featuring the current district after the 2010 redistricting:


MAP: Saint Petersburg Mayoral Election

On Tuesday, voters in Saint Petersburg, Florida voted in the first round of this year’s mayoral election, advancing incumbent Mayor Bill Foster and Rick Kriseman to the runoff election in November.

Below is a dot density map where one dot equals one vote. This graphic is heavily inspired by the Los Angeles Times maps of Los Angeles elections.


Entries and Exits: Map of a Day on the Washington Metro


The above graphic maps, per hour, entries and exits per station on a typical weekday on the Washington Metro, similar to this animation of the London Underground. Station data by hour was provided by WMATA for October 2012.

Red stations have more exits than entries in a given hour, while green stations have more entries. Early in the day, commuters flood in from outlying suburban stations and exit in the downtown core. During mid-day, suburban stations are quieter while downtown stations have balanced entries and exits. The commute flow reverses in the evening. We can divide stations into three types as land-use patterns and a station’s purpose can be discerned by their coloring and size behavior.

1) Job centers. The core contains most of the area’s commuter destinations, with Medical Center on the Red Line a notable outlier. During the lunch hour, ridership is higher than in bedroom communities. Riders exit these stations in the morning and enter them in the evening.

2) Bedrooms and park and rides. These stations, mostly outside the core, are nearly empty outside of rush hour. Commuters enter in the morning and exit at night.

3) Transportation hubs. These stations tend to remain white in the map with largely equal exits and entries as long-distance passengers use Union Station and National Airport. Pentagon, despite being home to the world’s largest office building, also sees even entries and exits during most of the rush hour with a large portion of transferring passengers using the Pentagon bus terminal.

4) Mixed-use areas. Arlington County stations between Rosslyn and Ballston are good examples of areas with both jobs and residents, giving them largely even entries and exits during rush hour.

Stations are mapped to their actual geographic location, which looks substantially different than the diagrammatic official map.

INTERACTIVE MAP: June 11 VA Democratic Primary by Polling Place

The following maps show precinct-level unofficial returns for statewide offices in the June 11, 2013 Virginia Democratic Primary.

Each dot represents one polling place, totals for polling places with more than one precinct are combined. Click to retrieve individual results, and use the zoom and pan tools to zero in on a neighborhood.

Democrats nominated State Sen. Ralph Northam and State Sen. Mark Herring to join gubernatorial nominee Terry McAuliffe. Republicans held a statewide nominating convention last month, which I mapped here.

Absentee ballots in Virginia are not broken down by precinct, and are not included in the maps.

For interactive county-level maps, check VPAP. I geocoded polling places obtained from the State Board of Elections directory in lieu of obtaining shapefiles from each locality.

These maps both look very similar. Both Northam and Herring assembled closely associated coalitions.

Last Updated: June 12th, 1:08 AM.
2508/2534 precincts (99% reporting)

Lieutenant Governor

    Candidate Votes Percent
    Ralph Northam 76,463 54.28%
    Aneesh Chopra 65,997 45.81%

Attorney General

    Candidate Votes Percent
    Mark Herring 71,037 51.63%
    Justin Fairfax 66,547 48.37%

GIF: Mapping EW Jackson’s RPV Convention Victory


The above map shows the winner of each city or county’s delegation from last month’s Republican Party of Virginia convention. A handful of counties and cities were combined into the same delegations, and that is reflected in the map.

If you haven’t heard of E.W. Jackson, this year’s Republican nominee for Lieutenant Governor in Virginia, by now, you certainly will by Election Day. After muscling out six competitors in four ballots at last month’s Republican Party of Virginia convention in Richmond, Democrats immediately reacted with glee. Jackson is a melon-smashing, gay-bashing, segregation-defending right-wing Tea Partier who blurs the lines between the truth and satire. Like it or not though, he led every round of balloting at the RPV convention and held his ground as the chaotic opposition scrambled from candidate to candidate. One wonders how many exhausted delegates leaving an all-day marathon balloting session thought they’d rather have an instant-runoff primary.

The convention format is not kind to moderates. Only diehards would stomach the thought of traveling for hours (the farthest reaches of Southwest Virginia are over 6 hours away from Richmond) to spend all day in a convention hall. Bill Bolling and Tom Davis knew this when faced with a convention for higher statewide office, and Tom Davis’s wife Jeannemarie (no conservative slouch herself, but this is within a Republicans-only electorate here) learned the hard way this time around.

Official RPV results are here.