Corporations based in the county include the co-headquarters of Amazon, several consulting firms, and the global headquarters of Boeing, Raytheon Technologies and BAE Systems Platforms & Services.

Land grants from the British Crown were awarded to prominent Englishmen in exchange for political favors and efforts as part of the county's early development.

On July 16, 1790, the Congress passed the Residence Act, which authorized the relocation of the capital from Philadelphia to a location to be selected on the Potomac River by U.S. President George Washington.

[9] The Act established the borders of the area that eventually became Arlington, but the citizens in the District were no longer considered residents of Maryland or Virginia, which represented the end of their federal representation in Congress.

[10] Prior to retrocession, residents of Alexandria County expected the proximity of the federal capital to result in higher land prices and the growth of regional commerce.

In 1862, the U.S. Congress passed a law that required that obligated owners of property in districts where active Confederate insurrections were occurring to pay their real estate taxes in person.

James A. Garfield, a Republican member of the U.S. House of Representatives who was a brigadier general in the Union Army during the Civil War and later became the 20th President of the United States, was an attorney on Hunter's legal team.

[17] The property included the former residence of Confederate General Robert E. Lee's family at and around Arlington House, which had been subjected to an appraisal of $26,810, on which a real estate tax of $92.07 was assessed.

Lawyers for the local chapter of the National Association for the Advancement of Colored People (NAACP) filed suit on behalf of a group of parents of both white and black students to end segregation.

The ensuing gentrification caused the mostly working and lower middle class white Southern residents to either be priced out of rent or in some cases sell their homes.

This permanently changed the character of the city, and ultimately resulted in the virtual eradication of this group over the coming 30 years, being replaced with an increasing presence of a white-collar transplant population mostly of Northern stock.

[citation needed] While a population of white-collar government transplant workers had always been present in the county, particularly in its far northern areas and in Lyon Village, the 1980s, 1990s and 2000s saw the complete dominance of this group over the majority of Arlington's residential neighborhoods, and mostly economically eliminated the former working-class residents of areas such as Cherrydale, Lyon Park, Rosslyn, Virginia Square, Claremont, and Arlington Forest, among other neighborhoods.

[34] In 2018, Amazon.com, Inc. announced that it would build its co-headquarters in the Crystal City neighborhood, anchoring a broader area of Arlington and Alexandria that was simultaneously rebranded as National Landing.

[52] The climate in the county is characterized by hot, humid summers, mild to moderately cold winters, and pleasant spring and fall seasons.

[78] 2023 marked the sixth consecutive year that the American College of Sports Medicine named Arlington the "Fittest City in America" in their annual Fitness Index.

Like most Virginia counties, Arlington has five elected constitutional officers: a clerk of court, a commissioner of revenue, a commonwealth's attorney, a sheriff, and a treasurer.

[99] In 2009, Republican Attorney General Bob McDonnell won Virginia by a 59% to 41% margin, but Arlington voted 66% to 34% for Democratic State Senator Creigh Deeds.

In the Virginia House of Delegates, Arlington is divided between the 45th, 47th, 48th, and 49th districts, represented by Mark Levine, Patrick Hope, Rip Sullivan, and Alfonso Lopez, respectively.

[116] A number of federal agencies are headquartered in Arlington, including the Air Force Office of Scientific Research, American Battle Monuments Commission, DARPA, Diplomatic Security Service, Drug Enforcement Administration, Foreign Service Institute, the DHS National Protection and Programs Directorate, Nuclear Waste Technical Review Board, Office of Naval Research, Transportation Security Administration, United States Department of Defense, United States Marshals Service, the United States Trade and Development Agency, and the U.S. AbilityOne Commission.

[119] Arlington is also the location of Washington, D.C. area regional offices for several consulting firms and is the global headquarters of many aerospace manufacturing and defense industry companies.

Although it is located in Arlington County, the United States Postal Service requires that "Washington, D.C." be used as the place name in mail addressed to the six ZIP codes assigned to The Pentagon.

[132] It was built from 689,000 short tons (625,000 t) of sand and gravel dredged from the nearby Potomac River[132] that were processed into 435,000 cubic yards (330,000 m3) of concrete and molded into the pentagon shape.

[134] During World War II, the earliest portion of the Henry G. Shirley Memorial Highway was built in Arlington in conjunction with the parking and traffic plan for the Pentagon.

Land for parking and roads was acquired by the exercise of eminent domain over the African-American neighborhood of Queen City, in East Arlington, displacing hundred of Black families.

Forty percent of Virginia's transit trips begin or end in Arlington, with the vast majority originating from Washington Metro rail stations.

This includes Metroway, the first bus rapid transit (BRT) in the D.C. area, a joint project between WMATA, Arlington County, and Alexandria, with wait times similar to those of Metro trains.

These services include DASH (Alexandria Transit Company), Fairfax Connector, PRTC OmniRide (Potomac and Rappahannock Transportation Commission), and the Loudoun County Commuter Bus.

[142][143] Capital Bikeshare, a bicycle sharing system, began operations in September 2010 with 14 rental locations primarily around Washington Metro stations throughout the county.

Founded in 1950 by the Religious of the Sacred Heart of Mary as Marymount College of Virginia, both its main campus and its Ballston Center are located on North Glebe Road, with a shuttle service connecting the two.

ASCA works to enhance and promote the region's international profile and foster productive exchanges in education, commerce, culture and the arts through a series of activities.