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.