1722: The Treaty of Albany forces Native Americans west of the Blue Ridge, and settlers began to move into Loudoun County.

1757: Loudoun is granted county status and named for Commander-in-Chief of the British and colonial forces in the French and Indian War, John Campbell, fourth Earl of Loudoun.

1758: Leesburg is founded.

1761: The first courthouse is built in the center of Leesburg.

1775: Loudoun County has the largest militia in Virginia.

1790: First census shows that Loudoun County has Virginia's highest county population.

1812: Loudoun's county clerk hides important documents, such as the Constitution, in the family home of Rokeby, during the British invasion of Washington, D.C.

1823: President James Monroe writes the Monroe Doctrine at Oak Hill in southern Loudoun.

1861: Civil War battle at Ball's Bluff.

Early 1960s: Construction of Dulles International Airport supports economic development.