Fairfax County is a county

County (United States)

In the United States, a county is a geographic subdivision of a state , usually assigned some governmental authority. The term "county" is used in 48 of the 50 states; Louisiana is divided into parishes and Alaska into boroughs. Parishes and boroughs are called "county-equivalents" by the U.S...

 in Virginia

Virginia

The Commonwealth of Virginia , is a U.S. state on the Atlantic Coast of the Southern United States. Virginia is nicknamed the "Old Dominion" and sometimes the "Mother of Presidents" after the eight U.S. presidents born there...

, in the United States. Per the 2010 Census, the population of the county is 1,081,726, making it the most populous jurisdiction in the Commonwealth of Virginia, with 13.5% of Virginia's population. The county is also the most populous jurisdiction in the Washington Metropolitan Area

Washington Metropolitan Area

The Washington Metropolitan Area is the metropolitan area centered on Washington, D.C., the capital of the United States. The area includes all of the federal district and parts of the U.S...

, with 19.8% of the MSA population, as well as the larger Baltimore–Washington Metropolitan Area, with 13.1% of the CSA

Combined Statistical Area

The United States Office of Management and Budget defines micropolitan and metropolitan statistical areas. Metropolitan and micropolitan statistical areas consist of one or more counties...

 population.

Fairfax was the first county in the United States to reach a six-figure

Number

A number is a mathematical object used to count and measure. In mathematics, the definition of number has been extended over the years to include such numbers as zero, negative numbers, rational numbers, irrational numbers, and complex numbers....

 median household income, and has the second-highest median household income

Highest-income counties in the United States

There are 3,141 counties in the United States. The source of the data is the U.S. Census Bureau and the data is current as of the indicated year. Independent cities are considered county-equivalent by the Census Bureau.-2011:...

 of any local jurisdiction in the United States after neighbor Loudoun County

Loudoun County, Virginia

Loudoun County is a county located in the Commonwealth of Virginia, and is part of the Washington Metropolitan Area. As of the 2010 U.S. Census, the county is estimated to be home to 312,311 people, an 84 percent increase over the 2000 figure of 169,599. That increase makes the county the fourth...

.

The county is home to the headquarters of intelligence agencies

United States Intelligence Community

The United States Intelligence Community is a cooperative federation of 16 separate United States government agencies that work separately and together to conduct intelligence activities considered necessary for the conduct of foreign relations and the protection of the national security of the...

 such as the Central Intelligence Agency

Central Intelligence Agency

The Central Intelligence Agency is a civilian intelligence agency of the United States government. It is an executive agency and reports directly to the Director of National Intelligence, responsible for providing national security intelligence assessment to senior United States policymakers...

, National Geospatial-Intelligence Agency

National Geospatial-Intelligence Agency

The National Geospatial-Intelligence Agency is an agency of the federal government of the United States with the primary mission of collecting, analyzing and distributing geospatial intelligence in support of national security. NGA was formerly known as the National Imagery and Mapping Agency ...

, and National Reconnaissance Office

National Reconnaissance Office

The National Reconnaissance Office , located in Chantilly, Virginia, is one of the 16 U.S. intelligence agencies. It designs, builds, and operates the spy satellites of the United States government.-Mission:...

, as well as the National Counterterrorism Center

National Counterterrorism Center

The National Counterterrorism Center is a United States government organization responsible for national and international counterterrorism efforts. It is based in a modern complex near McLean, Virginia called Liberty Crossing...

 and Office of the Director of National Intelligence.