In last week's article about cartograms, we discussed one type of thematic map (a map that displays a theme, such as poverty statistics or disease infection rates). This week, we'll look at some free programs to make choropleths - thematic maps that preserve distance and shape, but use colors or patterns to differentiate between different regions with different values.
Most of the maps we use look familiar to us: for instance, most Americans can recognize the shape of the continental United States whether it's appearing on a weather map or in a newspaper article about the economy. Sometimes, however, ordinary maps depicting geographic area aren't the most useful method of visualizing our information.
Neogeographer and community technologist Ben Sheldon posted a summary of his mapping presentation from the Technology 2.0 community event - it's a good overview of the topic and there are numerous great examples.
WaterGoodness is a new site allowing users to share and find water quality reports across the United States. The site combines water quality and pollution data from a variety of government sources with visitor reports of their local water quality.
Erek Dyskant submitted his Census Data Explorer project as part of the Sunlight Labs "Apps for America" challenge. While only a few layers (poverty and race) are available so far, this seems to be a relatively fast browser for visualizing census data at the tract or neighborhood level. It appears to be using OpenLayers and Google Maps, and of course the data comes from the Census Bureau. Good luck, Erek!
The US Forest Service has this Google Earth file (based on NASA satellite data) of near-real-time fires for the entire continental US
For those of you without access to Google Maps or Google Earth, CALFIRE (California Department of Forestry and Fire Protection) has plenty of up-to-date information on the fires, including frequently-updated incident maps covering the entire state.