500 years ago, the population of Virginia was concentrated rather than diffused consistently across the landscape. Native Americans lived in villages, or travelled in groups on traditional trails.
Today, the population of Virginia is concentrated in the modern equivalent of those villages, urban areas - or travelling in narrow corridors constructed by the Virginia Department of Transportation.
Those urban areas are defined by a Federal agency, the Office of Management and Budget (OMB). It has established criteria for the concentrations of people known as Metropolitan Statistical Areas and Micropolitan Statistical Areas:1
The criteria for a jurisdiction to be included in Metropolitan/Micropolitan Statistical Areas have changed, as population has grown. In 2013, the standards were:2
The definition of Standard Metropolitan Areas started before the 1950 Census. OMB does not intend for the boundaries to serve as a general purpose geographic framework... but the changing designations do reflect the increasing economic links between central cities and nearby jurisdictions, as suburbs have expanded and commuters travel longer distances to jobs in the urban core.
After the 1990 Census, Virginia's urban population was concentrated in 8 areas defined as Metropolitan Statistical Areas by the Federal government:
1. "Metropolitan and Micropolitan Statistical Areas Main," Census Bureau, http://www.census.gov/population/metro/ (last checked March 11, 2014)
2. "Revised Delineations of Metropolitan Statistical Areas, Micropolitan Statistical Areas, and Combined Statistical Areas, and Guidance on Uses ofthe Delineations ofThese Areas," Office of Management and Budget, OMB Bulletin No. 13-01, February 28,2013, http://www.whitehouse.gov/sites/default/files/omb/bulletins/2013/b13-01.pdf (last checked March 11, 2014)