This geovisualization shows county-level demographic data from the 2000 United States Census. The data consists of shapefiles and DBF database files (totalling approximately 20MB zipped) obtained from the
National Atlas, describing states, counties, cities, urban areas, roads, railroads, and airports. Demographics for each county include population, density, genders, median age, percent change since 1990, and proportions of major ethnic groups.
The visualization displays overview and detail maps alongside a list of states and territories. The detail map draws and labels natural and artificial areas of selected states, as determined by the checkboxes. The color used to fill each county is calculated using a bivariate mapping of two county-level demographic attribute functions — in the screenshot above, the percentage of people over 65 and the fourth root of population density.
The visualization allows comparison of the demographic function with population density and other demographic attributes, using parallel coordinate plots and a corresponding scatter plot matrix. A table view lists the counties of the selected states, using the same color-coding as the detail map. Two more table views list the cities and airports in selected counties.
Users can drag and stretch portals (the translucent gray regions) in the parallel coordinate axes to highlight certain counties in all the views. Counties for which all demographic values fall within the corresponding portal ranges are shown as bright blue shapes (in plots) or right-justified, boldface names (in tables). Portal-like map lenses drag and stretch several possibly overlapping geographic layers (for county names, roads, and urban areas) over limited rectangular portions of the map.
Users can also change the color gradient and edit the demographic functions dynamically, although the latter currently happens in the Improvise visualization design interface by modifying the corresponding expression in the lexicon editor.
Visualization (23.1 MB)