Univariate choropleth maps

Univariate choropleth map displays a single data set using different colors and shades. This particular map shows the elections from 2004 but this website shows each presidential election snice 1960. Shown on this map is a graph of the United States and all the counties in the lower 48 states. Each county or district shows a different color or shade of blue or red. The more red a county is, the high percentage of republican votes in this election and likewise for the democratic voters.

http://www.princeton.edu/~rvdb/JAVA/election2004/