Arlington County, Virginia area. The county is situated in Northern Virginia on the southwestern bank of the Potomac River directly across from Washington, D.C., of which it was once a part. With a land area of , Arlington is the geographically smallest self-governing county in the U.S., and by reason of state law regarding population density, has no incorporated towns within its borders. Due to the county's proximity to downtown Washington, D.C., Arlington is home to many important installations for the capital region and U.S. government, including the Pentagon, Reagan National Airport, and Arlington National Cemetery. Many schools and universities have campuses in
Arlington County, Virginia 2018 ParkScore ranking of the top 100 park systems across the United States, according to the ranking methodologies of the nonpartisan Trust for Public Land. The climate in this area is characterized by hot, humid summers and generally mild to cool winters. According to the Köppen Climate Classification system, Arlington County has a humid subtropical climate, abbreviated "Cfa" on climate maps. As of the 2010 census, there were: The population density was 8,309 people per square mile (2,828/km²), the highest of any county in Virginia. According to the US Census, the racial makeup of the county in 2012 was: There