1st American Regiment, also known as Jackson's Continental Regiment of 1783–1784, was the last unit in the Continental Army, retained after the close of the American Revolutionary War. This regiment, under the command of Colonel Henry Jackson of Massachusetts, was not the same unit as Jackson's Additional Continental Regiment of 1777, which had become the 16th Massachusetts Regiment in 1780 and had been disbanded in 1781. Equally, this regiment should not be confused with the First American Regiment of 1784–1791, which was originally commanded by Colonel Josiah Harmar, has remained in service to the present, and is now the 3d United States Infantry Regiment (The Old Guard).