Missouri Compromise Divides the Nation

President James Monroe: signer of the Missouri Compromise bills

The Missouri Compromise debate focused on two Constitutional issues regarding territories and the admittance of new states into the Union, in this case a slave state.

The Missouri Compromise debate represented the first time that the North and the South interjected the question of slavery into westward expansion. At issue was the meaning of two clauses in Article IV of the Constitution. To what extent did Congressional power extend to the territories and could a new state be admitted automatically or could Congress impose limitations on the new state’s constitution? The Missouri Compromise ignited passions in the North and the South, prompting Thomas Jefferson to liken the debate to a “fire bell in the night.” Additionally, the debate corresponded to other forces, notably in the South, championing state’s rights over Congressional and Judicial Nationalism.

The First Missouri Compromise Debate

The passage of the Missouri Bill in December 1819 was not the final step toward statehood. Missouri had begun the process in 1817. The December 1819 measure was an enabling act; statehood would be fully achieved after Congressional passage of a resolution once the state constitution had been received. This same process had been followed in the admittance of Ohio, Illinois, and Indiana.

The Missouri Territory, however, sought admittance as a slave state. Until the controversy, a Congressional balance resulted in eleven free states and eleven slave states. In response, the House Committee on Territories reported a bill that included an amendment attached by New York Representative James Tallmadge which outraged Southerners. The Tallmadge Amendment banned further slavery in Missouri and provided for the emancipation of slaves in Missouri upon attaining the age of 25.

Movement toward Compromise

Under the leadership of Speaker Henry Clay, a compromise was cobbled together that included admitting Maine as a free state and banning all further slavery above the 36/30 line through the Louisiana Purchase territory. Southerners countered that the 1803 Louisiana Purchase Treaty in Article III guaranteed the right to own slaves within the entire territory.

The Sixteenth Congress and Missouri Statehood

The next Congress grappled with Missouri statehood as soon as the electoral votes from the preceding election were received in their chambers. Missouri’s three electoral votes were discounted under pressure from the North which contended that Missouri was not yet a state. Further complicating matters was the Missouri state constitution that included two provisions onerous to the North. The first provision barred free blacks from entering Missouri and the second prohibited the Missouri legislature from ever emancipating slaves without the consent of owners.

Constitutional Issues

Article IV, Section 3, Clause I asserts that “New States may be admitted by the Congress into this Union…” Northern Congressmen interpreted this as conditional but Southerners saw it as an absolute. Anti-slavery men focused on the word, “may,” and asserted that Congress could reject applications for statehood, in this case based on the Missouri constitution.

Clause II of the same section also gave the Congress the power to, “…make all needful Rules and Regulations…” in regard to territories. This clause would begin a long Congressional battle over the extension of slavery, particularly after the Mexican Cession in 1848. The issue was only partially resolved by the 1857 Dred Scott Decision by the Supreme Court.

Missouri Admitted to the Union

President Monroe signed the final legislation admitting Missouri as a slave state on August 10, 1821. The 36/30 line would divide the nation into free and slave and keep the national peace until 1848. Jefferson, reflecting on the debate and the passions, wrote “This is a reprieve, not a final sentence.”


  1. Alfred H. Kelly and Winfred A. Harbison, The American Constitution: Its Origins and Development, 5th Ed. (W. W. Norton & Company, 1976)
  2. Frederick Merk, History of the Westward Movement (Alfred A. Knopf, 1978)
  3. Page Smith, The Shaping of America: A People’s History of the Young Republic, Vol. III (McGraw-Hill Book Company, 1980)