Sunday, December 31, 2006

Mapmaker, Mapmaker, Make Me a Map

If the Internet were a person, her achievements would be myriad: community-based knowledge creation, an expansive index of fetish pornography, instant access to a world of current events, free real-time communication with anyone one the planet, and universal access to massive libraries of publicly-funded data reserves! The World Wide Web, coupled with her sister Geospatial Data, brings you the National Atlas, a two-dimensional gold mine of place-based information about the United States.

Yes! Geospatial data! That's up there with Lego in my nerdly pleasure hierarchy.

The National Atlas has many awesome features - printable maps of every presidential election result since 1789, dynamic maps of monthly vegetation growth in America, downloadable raw data on which the maps are based - but the coolest way to impress your friends is with the National Atlas Map Maker. Go ahead, indulge in a few hours of exploration. Each layer is a tasty little nugget of data visually describing our country's energy use, geology, economic health, or some other nifty construct. Most data are disaggregated by county, which is neat when trying to illustrate, for example, how different San Francisco is from, say, Inyo County.

Not only are the maps a fun and easy way to absorb information about your United States, they're also a handy tool in political debates. Is your racist Midwestern uncle claiming that Mexicans are taking his job? Go ahead and show him that his county is less than 3% Hispanic, then let him observe the apparent lack of correlation between Hispanic population and jobs per capita and unemployment rates! You'll be the life of the party.

Or show all your cheese-eating in-laws that colon cancer rates are highly concentrated in the upper Midwest, then illustrate that the American West enjoys lower cancer rates than everyone else. Everyone likes a know-it-all.

Or, less argumentatively, simply peruse cool information like vegetable harvesting acreage or fertility rates among women over 40 or the location and magnitude of earthquakes since the late 16th century. (California leads the pack in all three categories.)

A caveat: Raw number data in the same category might not be easily compared across time periods due to varied distribution of color codes from one map to the next. For example, in the map of "Percent of Population: White" for 2000, the bright yellow indicates a percentage range of 0.1 to 33.1; in the 1980 map of the same variable, the bright yellow represents 6.332 to 38.928 percentage points. This distribution is based on a formula I learned about in my brief ArcGIS training; I forgot the name of the formula, but it distributes ranges in a more informative way than a simple linear distribution would.

Hopefully USGS will include a map illustrating climate change over the centuries and degades once it's available. I look forward to the depressing news.

Happy mapmaking!


Thinker said...

Rebecca, thank you for posting these links. I was not aware of this site, but plan to spend time examining it.

One correction you might want to make. Your link to the Presidential Election Maps leads to the dynamic vegetation maps page. Exploring the site a bit, I found a Presidential Elections map page at

Rebecca C. Brown said...

Thanks for the headsup! Link has been changed.