Skip to content

Missouri Compromise (1820)

Event Overview

The Missouri Compromise was a legislative agreement passed by the U.S. Congress in 1820 to resolve a dispute over the extension of slavery into new territories following Missouri’s application for statehood.

At the time, the United States consisted of an equal number of free and slave states. Missouri’s admission as a slave state threatened that balance.

Legislative Sequence

  • 1819
    • Missouri applied for admission to the Union as a slave state.
    • During congressional debate, an amendment was proposed to prohibit the further introduction of enslaved people into Missouri and to provide for gradual emancipation.
    • The amendment passed in the House of Representatives but failed in the Senate.
  • 1820
    • Congressional negotiations produced a multi-part compromise:
      • Missouri would be admitted as a slave state.
      • Maine would be admitted as a free state, preserving numerical balance in the Senate.
      • Slavery would be prohibited in the remaining Louisiana Purchase territory north of latitude 36°30′, except for Missouri.
  • The compromise was passed by Congress and signed into law by President James Monroe in March 1820.

Explicit Provisions

  • State Admissions
    • Missouri: admitted as a slave state.
    • Maine: admitted as a free state.
  • Territorial Rule
    • Slavery prohibited in territories north of the 36°30′ parallel.
    • Slavery permitted south of that line.
  • Scope
    • Applied only to territories acquired through the Louisiana Purchase.
    • Did not alter the status of slavery in existing states.

Contemporary Framing

  • Congressional debates framed the compromise as:
    • a necessary measure to preserve the Union
    • a temporary solution to sectional disagreement
    • a means of preventing immediate political rupture
  • Slavery itself was not resolved or redefined at the federal level.
  • The compromise explicitly postponed resolution of slavery’s constitutional status.

Immediate Outcomes

  • Admission of Missouri and Maine proceeded without further delay.
  • Sectional balance in the Senate was temporarily preserved.
  • Slavery’s expansion was formally regulated by geographic boundary rather than national policy.

Documentary Evidence (Attachments to Add)

(Primary sources to attach when available)

  • Text of the Missouri Compromise legislation (1820)
  • Congressional debate transcripts (House and Senate, 1819–1820)
  • Correspondence from key legislators discussing the compromise
  • Presidential correspondence or messages related to the bill

Notes on the Record

  • The Missouri Compromise represented the first major federal attempt to manage slavery’s expansion through territorial partition.
  • The legislation treated slavery as a negotiable political variable rather than a resolved constitutional issue.
  • The compromise established a precedent for resolving sectional conflict through balance and deferral.