There are 37 US Post Offices in Fairfax County serving a total of 931,586 residents equating to 25,178 residents per post office. It's estimated that approximately 1,486,915 packages are handled across the 37 county post offices annually. Fairfax County, officially the County of Fairfax, is a county in the Commonwealth of Virginia. As of the 2010 census, the population was 1,081,726, in 2015, it was estimated at 1,142,234, making it the most populous jurisdiction in the Commonwealth of Virginia, with 13.6% of Virginia's population. The county is also the most populous jurisdiction in the Washington-Arlington-Alexandria, DC-VA-MD-WV Metropolitan Statistical Area, with 19.8% of the MSA population, as well as the larger Washington-Baltimore-Arlington, DC-MD-VA-WV-PA Combined Statistical Area, with 13.1% of the CSA population. The county seat is the City of Fairfax. Fairfax was the first U.S. county to reach a six-figure median household income and has the second-highest median household income of any local jurisdiction in the United States after neighbor Loudoun County. The county is home to the headquarters of intelligence agencies such as the Central Intelligence Agency, National Geospatial-Intelligence Agency, and National Reconnaissance Office, as well as the National Counterterrorism Center and Office of the Director of National Intelligence. The county is also home to seven Fortune 500 companies, including three with Falls Church addresses."