Thursday, January 03, 2008

Sales Heat Map: Zip Code 20007

With the holidays and 2007 behind us, I thought I'd restart my heat mapping effort. As I've mentioned in earlier posts, I've been analyzing 2007 residential sales per zip code per square to "heat map" the sales. In other words, I've taken 2007 home and condo sales through October 2007 [the last full month of data I have in my database] and mapped the average and median sales price for each square in the zip code.


All properties in the District - for that matter, everywhere in the US - are identified by the square and lot on which they are located. I use Google Maps' KML technology to create my heat maps. I haven't found an authoritative reference with the geocodings I need to map each square in the District so I've had to improvise. The resulting map may be a little imprecise, but I believe it's close enough to give you an idea of what's going on.


According to my database, the District recorded 403 sales in zip code 20007 through the end of October. After excluding anything the District has not designated a home [rowhouse, detached, or semi-detached] or a condo, I'm left with 380 sales to heat map. Of those sales:

  • Condos: 174
  • Row houses: 133
  • Detached homes: 50
  • Semi-detached homes: 23

The chart below shows the distribution of sales in the area. The average sales price for zip code 20007 during this period was $935,986; 72.37% of all home and condo sales were at this price or lower. The median price was $716,500.

Total dollar volume for 2007 sales in 20007 during the period was $355,674,637.

Heat Map

My data is granular enough to allow me to 'heat map' the District on a per square basis. The interactive map below shows sales data for zip code 20007. I emphasize interactive because you can click on an icon on the map below and its data will be displayed; you can move and pan the map, too. You do not have to leave this site.

The legend at right explains the colors used for each pin on the map. For example, a yellow pin on a square means the average price for the square is between $200,001 and $400,000. You'll get the exact data when you click the pin.

View Larger Map

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