The data shown is from the U.S. Census Bureau’s SF1 and TIGER data sets for 2010. See the map pack for this data. The map is multi-scale – it switches from state to county, to tract, to block group data as the map zooms in. The polygon data was shorelined and selected rivers and lakes were also erased from the boundaries to give a more familiar look at specific scales.
At each scale, a simple popup shares a few key statistics in a paragraph and displays a chart of housing by type of ownership.
The thematic classifications are centered around the U.S. average for housing with mortgages (about 40%). The center classification is characterized as “Average.” Its breakpoints are based on one-half standard deviation around the mean. Breakpoints for the “Low” and
“High” classes are also determined from one-half standard deviation (9.7%). “Very Low” and “Very High” classes capture the remaining values.
The thematic colors use colors chosen to emphasize the “high” end of the values. Darker colors are used to represent high values, while lighter colors represent low values. The “Average” class color is neutral. As you zoom into the map, a stroke is added to the polygon boundaries to delineate the county, tract and block group boundaries without allowing them to dominate the map (as is the case with black, white or other strong colors for boundaries).
The light gray canvas basemap was selected for this web map to draw attention to the thematic content.