'Loudoun County, VA' definitions:

Loudoun -- U.S. County in Virginia

From: Gazetteer 2000
Name :
Loudoun -- U.S. County in Virginia
Population (2000) :
169599
Housing Units (2000) :
62160
Land area (2000) :
519.851295 sq. miles (1346.408615 sq. km)
Water area (2000) :
1.249800 sq. miles (3.236968 sq. km)
Total area (2000) :
521.101095 sq. miles (1349.645583 sq. km)
Located within :
Virginia (VA), FIPS 51
Location :
39.064634 N, 77.568819 W