I love looking at maps. Good maps contain high data density and if you are already familiar with the region being described on the map, looking at the map evokes your memories of passing through the area defined. A good map is a piece of art.

The current issue of the Univ. Chicago Mag. May 2011 describes the map work of Eric Fischer, an engineer at Google.

One of his projects was to create a Flickr photostream with maps of various cities with colored lines showing people’s inferred path based on the timestamps of their geocoded photos uploaded to Flickr or Picasa. The project is called the Geotaggers’ World Atlas. The map of Seattle area is shown below.


Map showing paths of people who shared photos taken in Seattle. Image from Eric Fischer in the Geotaggers’ World Atlas

The color of the lines shows the estimated speed of the photographer. Black is by foot, red is by bike, and green is by car. You’ll notice that the densest set of lines are in downtown Seattle and most of them are black. The fewest lines are in the suburbs, and most of them are green. Even though the population on either sides of Lake Washington are similar, most of the photos are taken on the Seattle side. More proof that the eastside is boring.

Using the same data, Mr Fischer creates another set of maps that teases out whether the photographs are taken by tourists or locals. He does this by first seeing if there is a single city in which the user’s pictures span more than a month. If so, the user is considered a local in that city. All other pictures taken by the same user outside that city (and which have timestamps that span less than a month) are considered tourist pictures. This provides two interesting bits of data. First, do locals and tourists take pictures of different things? Second, do some cities attract more photo-happy tourists than others.

In another project, Mr Fischer has created a set of maps of major U.S. cities showing the level of racial segregation in 2010. Normally, maps like these start with neighborhood boundaries and then use a chloropleth technique to indicate the population density of each race in the neighborhood. However, with the power of computers today, it is now possible to reverse the process. One can display households on the map and let the colors define the boundaries of neighborhoods.

Mr Fischer’s maps do this by placing a colored dot on a map to represent 25 households of a particular race (African in blue, Caucasian in red, Asian in green, and Other in yellow) or Hispanic origin regardless of race (orange). He uses U.S. Census self-reported race and ethnicity data from the both 2000 and 2010 census at the census block level. A map of Seattle (it also includes most of King County and parts of Kitsap County) is shown below.

As can be seen in the map,  Seattle has a smaller proportion of blacks than any other large urban area in the U.S., at 6.1%. The black population is concentrated in neighborhoods south of downtown. Asians make up a larger proportion of the population at 13.2%. They are also concentrated south of downtown but also tend to be dispersed throughout the region with pockets in Bellevue (east of Lake Washington), Renton, and Kent (both south of Bellevue).


Map showing Seattle’s racial distribution. Image from Eric Fischer

The idea for the maps comes from Bill Rankin’s map of Chicago that is available at a website called Radical Cartography. This site has a variety of other maps for cities, the United States, the world, and even the universe.

[Update: I corrected an error in the description of the race maps. Pacific Islanders are included in the Other race category, not in the Asian category. Pacific Islanders make up 0.5% of the Seattle population. I subtracted this from the population data for Asians.]