Maine became the 23rd state of the United States on March 15, 1820, as part of the Missouri Compromise. Previously a district of Massachusetts, Maine sought statehood to gain independence from its more distant governing body. Its admission was paired with Missouri's entry as a slave state, maintaining the balance of power between free and slave states in the Union. This compromise highlighted growing tensions over slavery in the U.S. that would continue to escalate in the following decades.
