There are 16 US Post Offices in Loudoun County serving a total of 184,464 residents equating to 11,529 residents per post office. It's estimated that approximately 294,425 packages are handled across the 16 county post offices annually. Loudoun County (/\u02c8la\u028ad\u0259n/ LOWD-\u0259n) is a county located in the Commonwealth of Virginia. In 2015, the population was estimated at 375,629, making it the third-most populous county in Virginia. Loudoun's county seat is Leesburg. Loudoun County is included in the Washington\u2013Arlington\u2013Alexandria, DC\u2013VA\u2013MD\u2013WV Metropolitan Statistical Area. As of 2011, Loudoun County had a median household income of $119,134. Since 2008 the county has been ranked first in the United States in median household income among jurisdictions with a population of 65,000 or more."