The 1st District of Columbia Cavalry was a Union Army cavalry regiment which fought in the American Civil War.

Four cavalry companies were formed from June to December 1863, under the command of Colonel Lafayette C. Baker for service in the defenses of Washington, D.C.; in November it was transferred to the Department of Virginia and North Carolina.

Eight companies which had been raised in Augusta, Maine were attached to the regiment in early 1864.

The regiment participated in the Siege of Petersburg during the remainder of 1864 and early 1865.

After fighting in the Appomattox Campaign, the regiment served in garrison roles in Virginia until mustering out on October 26, 1865.