This service is Virginia data from the 2011 release of the Census Bureau TIGER/Line Shapefile for national counties or equivalent boundaries (tl_2011_us_county.shp)
The TIGER/Line Files are shapefiles and related database files (.dbf) that are an extract of selected geographic and cartographic information from the U.S. Census Bureau's Master Address File / Topologically Integrated Geographic Encoding and Referencing (MAF/TIGER) Database (MTDB). The MTDB represents a seamless national file with no overlaps or gaps between parts, however, each TIGER/Line File is designed to stand alone as an independent data set, or they can be combined to cover the entire nation.
The primary legal divisions of most States are termed counties. In Virginia, cities are independent of any county organization and thus constitute primary divisions. These incorporated places are known as independent cities and are treated as equivalent to counties for purposes of data presentation.
The 2010 Census boundaries for counties and equivalent entities are as of January 1, 2010, primarily as reported through the Census Bureau's Boundary and Annexation Survey (BAS).
