The land that today comprises Arlington County was originally carved out of Virginia as part of the nation's new capital district. In 1847, the land was returned to the state of Virginia, although it was known as Alexandria County until 1920, when the name was changed to avoid confusion with the city of Alexandria.

The county was named to honor Arlington House, built by George Washington Parke Custis, a descendant of Martha Washington whose daughter married Robert E. Lee. The Lees lived in Arlington House on and off until the onset of the Civil War in 1861. After the first Battle of Bull Run, at Manassas, several Union soldiers were buried here; the beginnings of Arlington National Cemetery date from that time. The Arlington Memorial Bridge leads directly from the Lincoln Memorial to the Robert E. Lee Memorial at Arlington House, symbolically joining these two figures into one Union after the Civil War.

Arlington has long been a residential community, with most people commuting into Washington to work and play. In recent years, however, the suburb has come into its own, booming with business, restaurants, and nightlife, giving residents reasons to stay put and tourists more of an inducement to visit.