Maine became a state on March 15, 1820, entering the Union as the 23rd state. Its admission was the free-state half of the Missouri Compromise, a congressional bargain that paired Maine’s entry with Missouri’s as a slave state to keep the Senate’s sectional balance intact. The question of when Maine became a state has a simple date for an answer, but the date itself exists because of a national fight over slavery that nearly stopped the admission from happening at all.
Why Maine Was Seeking Statehood in the First Place
For nearly 170 years, Maine was not a state but a district of Massachusetts. The arrangement went back to 1652, when Kittery residents swore allegiance to the Massachusetts Bay Colony, with other coastal communities following by 1658.1Maine Memory Network. Maine’s Colonial History Under Massachusetts Massachusetts used military pressure to extract “articles of submission” from Maine leaders, effectively making the territory a “colony within a colony.”2Secretary of the Commonwealth of Massachusetts. Did You Know: Maine Maine had no legislature or executive of its own; its delegates traveled to Boston to sit in the Massachusetts General Court.3Maine Memory Network. Maine Bicentennial
Separation sentiment grew after the Revolution but kept failing at the ballot box. Between 1792 and 1819, at least six formal separation votes went to the Massachusetts General Court, with others dismissed for insufficient ballots.3Maine Memory Network. Maine Bicentennial Coastal merchants who depended on Boston trade opposed independence; frontier settlers favored it. The War of 1812 broke the stalemate. British forces seized Maine’s coast east of Penobscot Bay, and the Massachusetts legislature refused to send help, focusing instead on defending its own territory.4Maine Secretary of State. The War of 1812 and Maine Statehood The abandonment pushed the merchant class into the separation camp.
In 1819, Massachusetts finally agreed to let Maine go. The Massachusetts Senate passed the separation bill 26 to 11, the House followed 193 to 59, and Governor John Brooks signed the Act of Separation on June 19, 1819. The act required Maine voters to approve separation by a margin of at least 1,500 votes. On July 26, 1819, they did, 17,091 to 7,132.5Maine Memory Network. The Act of Separation
Delegates convened in Portland on October 11, 1819, drafted a state constitution by October 29, and presented it to Maine voters, who approved it in January 1820.6Maine Legislature. History of Maine The new constitution eliminated property requirements for voting, extended suffrage to all male U.S. citizens 21 and older including Black men, and disenfranchised women, the poor, and “Indians not taxed.”7Maine Memory Network. Constitution of the State of Maine By the start of 1820, Maine had done everything it could do on its own. What remained was congressional approval, and that is where the trouble started.
How the Missouri Compromise Delayed and Shaped the Date
Maine’s admission bill arrived in Congress during a crisis over slavery that had already deadlocked another state’s application. In February 1819, Representative James Tallmadge Jr. of New York had proposed amendments to Missouri’s statehood bill that would have barred new slavery in Missouri and required gradual emancipation. The House passed the amendments; the Senate rejected them; the dispute carried into the next Congress.8U.S. House of Representatives. The Tallmadge Amendment
At that moment the Union stood at eleven free states and eleven slave states. The Senate’s balance of power depended on holding that count even. Southern senators would not let Maine come in as a free state unless Missouri came in with it as a slave state. On January 6, 1820, the Senate formally tied the two together by attaching a Missouri admission amendment to the Maine bill.9U.S. Capitol Visitor Center. Amendment to the Bill for Admission of Maine
Speaker of the House Henry Clay brokered the final package, which had three parts: Maine would enter as a free state, Missouri would enter as a slave state, and slavery would be prohibited in the remainder of the Louisiana Purchase territory north of the 36°30′ latitude line. That geographic line came from an amendment by Senator Jesse Thomas of Illinois.10U.S. Census Bureau. Maine Statehood and the Missouri Compromise
The procedural moves in the final days mattered. The House passed the compromise bill on March 2, 1820. The following day, pro-slavery representatives moved to reconsider. Clay ruled the motion out of order until routine business finished, quietly signed the bill during the window, and sent it to the Senate before his opponents could reopen the vote. A biographer later called it the “neatest and cleverest parliamentary trick ever sprung in the House.”11U.S. Senate. The Missouri Compromise
President James Monroe signed the Missouri Compromise on March 6, 1820. He had worked privately to secure its passage, corresponding with Virginia Senator James Barbour and warning he would veto any bill that imposed restrictions on Missouri not applied to other states.12University of Virginia – Miller Center. James Monroe Key Events Nine days later, on March 15, 1820, Maine was officially admitted to the Union.10U.S. Census Bureau. Maine Statehood and the Missouri Compromise
For many in Maine the compromise sat uneasily. John Holmes, one of the state’s first U.S. senators and a leader of the separation movement, voted for the deal and then wrote a public letter defending his choice. Thomas Jefferson received a copy and wrote back with his well-known warning that the slavery question would eventually tear the Union apart.13Maine Memory Network. John Holmes and the Missouri Compromise
The compromise itself held for 34 years. Congress repealed it with the Kansas-Nebraska Act of 1854, and in 1857 the Supreme Court declared it unconstitutional in Dred Scott v. Sandford.14National Archives. Missouri Compromise Maine’s statehood, of course, was not undone.
What Happened on March 15, 1820
When Maine formally entered the Union, its new constitution took effect and its first government began operating. William King, a wealthy Bath merchant and shipbuilder who had commanded the Maine militia during the War of 1812, became the first governor. The constitutional convention had elected him 153 to 1.15Maine Public. How William King Overcame Challenges to Become Maine’s First Governor His tenure was short. On May 28, 1821, he resigned to accept an appointment from President Monroe to negotiate a treaty with Spain.16Digital Maine. Governor William King Papers During his year in office, his administration established the state’s Supreme Judicial Courts and Courts of Common Pleas and built out the basic machinery of state government.
Portland served as the first capital, with the understanding that the arrangement was temporary because the city sat at the southern tip of the state.17Maine State Legislature. History of the State House Massachusetts did not entirely let go even after statehood. The commonwealth kept ownership of half the public land in Maine until Maine bought it back in 1853.2Secretary of the Commonwealth of Massachusetts. Did You Know: Maine
Statehood Didn’t Settle Maine’s Borders
Admission to the Union in 1820 did not fix Maine’s northern boundary. The 1783 Treaty of Paris had left the line between Maine and British-controlled New Brunswick poorly defined, and both sides claimed overlapping territory in the Aroostook region. A proposed compromise from King William of the Netherlands in 1831 was accepted by Britain but rejected by the U.S. Senate under pressure from Maine.18Digital Maine. The Aroostook War
The dispute escalated in February 1839 into the Aroostook War, sometimes called the “Bloodless War.” British troops marched from Quebec, Maine appropriated $800,000 and called for 10,000 militia volunteers, and Congress authorized 50,000 troops and $10 million. President Martin Van Buren sent General Winfield Scott to Augusta, and on March 21, 1839, Scott and British negotiator Sir John Harvey reached a truce. No shots were fired.19Encyclopaedia Britannica. Aroostook War
Permanent resolution came with the Webster-Ashburton Treaty, signed on August 9, 1842, by U.S. Secretary of State Daniel Webster and British envoy Lord Ashburton. The treaty established the boundary using specific geographic landmarks, opened the St. John River to navigation by both nations, and required the United States to pay Maine and Massachusetts $300,000 for their agreement to the new line. A joint commission was directed to meet in Bangor on May 1, 1843, to survey and mark the border.20Yale Law School – Avalon Project. The Webster-Ashburton Treaty The map of Maine as it exists today took shape 22 years after statehood, not on the day it was admitted.