Democrat Jim Webb defeated incumbent Senator George Allen by the slim margin of 49.6 to 49.2 percent in 2006. However, that margin increased to 58.1 to 40.7 percent in favor of the Democratic challenger in the counties and cities of Northern Virginia, whereas Webb ran behind Allen somewhat, 46.1 to 52.7 percent, in the remainder of the commonwealth. Webb carried Fairfax County, Prince William County, and Loudoun County, as well as the more urban areas of Arlington, Alexandria, and Falls Church. Allen's sole wins in Northern Virginia were the cities of Manassas and Manassas Park, winning the latter two only by the narrow margins of 3.54 and 2.38 percent, respectively.
