Lincoln County is located in the eastern part of the U.S. state of Missouri. As of the 2020 census, the population was 59,574. Its county seat is Troy. The county was founded December 14, 1818, and named for Major General Benjamin Lincoln of the American Revolutionary War.

Benjamin Lincoln was an American army officer. He served as a major general in the Continental Army during the American Revolutionary War. Lincoln was involved in three major surrenders during the war: his participation in the Battles of Saratoga contributed to John Burgoyne's surrender of a British army, he oversaw the largest American surrender of the war at the 1780 siege of Charleston, and, as George Washington's second in command, he formally accepted the British surrender at Yorktown.