Here’s a 12-second movie that places a year’s accumulation of murders on a map. The Office of the Chief Technology Officer of the District of Columbia has created a rich repository of public data, the Data Catalog. The first data set I looked at was Crime incidents (ASAP) 2011, culled from their Analytical Services Application. This data includes the date of the crime incident, the offense, and the geographic coordinates, which makes mapping easy.

Like my previous project with Capital Bikeshare’s open data (see Watching Bikeshare Stations Grow Unbalanced), I used Processing to create a QuickTime movie. The first movie shows the city’s 108 homicides in 2011, accumulating red circles at each location over the course of a year. For comparison, a second movie shows all 32,739 crimes reported for the same period.

For homicides, the starkest geographic difference is east and west of Rock Creek. The center of gravity for homicides is at Maryland Ave and G St NE (38.89849, -76.98695).

The second animation shows all crimes over the same period. The colors represent two categories. Red circles are for violent crimes (homicide, assault, robbery, and sex abuse), while blue circles are used for property crimes (theft, theft from auto, burglary, stolen auto, and arson). The city has more details about their data definitions on their Crime Incidents page.

There are a few anomalies in the data. The dot southeast of the District’s boundary is on the Suitland Parkway, just outside the Suitland Federal Center in Maryland. The data gives the coordinates as 38.846252, -76.93704; however, the address is 3400 B/O 23rd St SE. I don’t know why the coordinates don’t match the address. Similarly, three crimes have coordinates at Arlington National Cemetery, though the address is 3300 B/O N St NW. I also found two crimes with coordinates that place them in West Virginia. Odder still are the 19 crimes with coordinates in Antartica, at -72.61009, 48.202843, though the address is listed as 2000 B/O Maryland Ave NE. I did not correct the data, so these “distant” crimes are not displayed. 255 crimes (0.8% of the total) have coordinates of 0, 0. Some of those have addresses listed; none of them are included in the map.

The background image is the Nightvision map, courtesy of MapBox.

Animated Map of Homicides in Washington, DC

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