Missouri royalty: Former President Harry S. Truman (left) hosts President Lyndon B. Johnson at Truman's home in Independence, Missouri, in October 1968. At left is Truman's daughter, Margaret, and at right is former first lady Bess Truman. | AP Photo Missouri enters the Union, Aug. 10, 1821

On this day in 1821, Missouri entered the Union as the 24th state. It was the first state located entirely west of the Mississippi River.

By 1818, the Missouri Territory, part of the Louisiana Purchase of 1803, had gained enough settlers to qualify for statehood. Its settlers, however, had come mostly from the South, and they expected it would be a slave state.


When a Missouri statehood bill came before the House, Rep. James Tallmadge of New York proposed amending the measure to bar bringing slaves into the contemplated new state and providing for the ultimate emancipation of all slaves born in Missouri. The House approved that approach in 1819, but the Senate refused to go along.

In early 1820, a bill to admit Maine passed the House. Alabama had come into the Union as a slave state in 1819. With Alabama’s admission, there were an equal number of senators from free and slave states. Since Maine would enter as a free state, proponents of admitting Missouri as a slave state argued that by pairing the two, parity would be retained at 12 states each.

The Senate then voted to bar slavery in the rest of the Louisiana Purchase north of the southern boundary of Missouri — except in Missouri. Although the House rejected that proposed compromise, Senate-House conferees finally agreed that Missourians could adopt a constitution that permitted slavery.

But the House rebelled anew when a drafted state constitution barred allowing free blacks to settle in Missouri. The territorial legislature backed down and pledged that nothing in its constitution could be interpreted as abridging the rights of U.S. citizens. (Slaves were not citizens.) The deal, known as the Missouri Compromise, held until 1854, when it was superseded by the Kansas-Nebraska Act. (The U.S. Supreme Court ultimately ruled in 1857 that the Missouri Compromise was unconstitutional.)

In 1861, when other slave states seceded to trigger the Civil War, Missouri chose to remain in the Union. Missourians fought on both sides of the conflict.

Located on the Mississippi and Missouri rivers, the state was an important hub of transportation and commerce in early America; the Gateway Arch in St. Louis stands as an enduring monument to Missouri’s role as the “Gateway to the West.” At 630 feet, the arch is the country’s tallest man-made monument. Completed in 1965, the structure was built to commemorate the city’s importance in settling the West following President Thomas Jefferson’s Louisiana Purchase.

SOURCE: U.S. LIBRARY OF CONGRESS