This thematic map presents the median age of people in the United States in 2009. The 2009 Median Age is based on the age of each person in complete years.
Median age is calculated from the distribution of age by five-year groups. These data are ESRI's 2009 estimates.
The geography depicts states at greater than 25m scale, counties at 1m to 25m scale, Census Tracts at 250k to 1m scale, and Census Block Groups at less than 250k scale.
The map is designed to be displayed with semi-transparency of about 50% for overlay on other basemaps, which is reflected in the legend for the map.
ESRI 2009/2014 Demographic Data – ESRI analysts update more than 15,000 demographic attributes for eleven geographic levels by combining detailed information from multiple sources. See Updated Demographics for more information.
Coordinate System: WGS 1984 Web Mercator
Tiling Scheme: Google Maps/Bing Maps