Westward Expansion and Native American Removal, 1803-49 ยป The Missouri Compromise

What you'll learn this session

Study time: 30 minutes

Edexcel spec: Paper 2 Section B, Breadth study B1, Key topic 2

  • Why Missouri's request to join as a slave state caused a crisis in 1819
  • The terms of the Missouri Compromise of 1820, including the 36°30′ line
  • Why the Compromise mattered for the balance between free and slave states
  • How slavery in national politics in 1820 differed from 1809

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A growing nation, a growing problem

By 1819 the USA was spreading west fast. New states were joining the Union, and each new state raised the same question: would slavery be allowed there? In the North most states had ended slavery or were ending it. In the South the economy depended on enslaved labour, especially on cotton and tobacco plantations.

Key terms:

  • Sectional conflict: a quarrel between different regions (sections) of one country, here the North and the South, over their different interests.
  • Free state: a state where slavery was not allowed.
  • Slave state: a state where slavery was legal.
  • Missouri Compromise: the deal made by Congress in 1820 to settle the argument over Missouri and slavery in the western lands.
  • 36°30′ line: a line of latitude (an imaginary line running east to west on a map) drawn across the Louisiana Purchase land. North of it slavery was banned (apart from in Missouri). South of it slavery was allowed.

Why the balance mattered

Every state sends two senators to the Senate, however big it is. By the end of 1819, with Alabama's admission, there were 22 states: eleven free and eleven slave. This balance meant neither side could pass laws in the Senate without the other. The South was afraid that if free states outnumbered slave states, Congress might one day attack slavery. The North was afraid of a growing Southern hold on the national government.

The House of Representatives worked differently. Seats there depend on population, and the North had more people, so it had a majority in the House. The Senate was the South's protection.

The crisis of 1819

Missouri was part of the land bought in the Louisiana Purchase. By 1819 it had many settlers, including thousands of enslaved people. It asked to join the Union as a slave state.

📢 The North's anger

In February 1819 James Tallmadge, a member of the House of Representatives from New York, proposed an amendment (a change added to a bill). No more enslaved people could be brought into Missouri, and children born to enslaved parents there would be freed at the age of 25. The House, with its Northern majority, passed it.

⚔️ The South's fury

The Senate, with its balance of free and slave states, threw the amendment out. Southerners said Congress had no right to tell a new state what to do about slavery. Northerners said Congress controlled the western lands and could set conditions. The two houses were deadlocked.

The quarrel was about power as much as about slavery. If Missouri joined as a free state, the free states would be ahead in the Senate for the first time. If it joined as a slave state, the South would be ahead.

The Missouri Compromise, 1820

Congress found a way out in 1820, with Henry Clay, the Speaker of the House, playing a leading part in the deals. It had three parts:

  • Missouri would join as a slave state.
  • Maine would join as a free state. Maine had been part of Massachusetts and had asked to be a separate state. Its admission kept the Senate balanced, 12 free states to 12 slave states.
  • The 36°30′ line: in the rest of the Louisiana Purchase land north of this line, slavery was banned. South of the line, slavery was allowed. Missouri lay mostly north of the line, but was the exception.

President Monroe signed the law on 6 March 1820. Maine became a state that month. Missouri's story took longer. Its new constitution tried to stop free Black people from entering the state, which angered the North, and Congress needed a second deal before Missouri was admitted in August 1821.

Why was it significant?

  • It kept the balance. The Senate stayed level, so the South kept its protection.
  • It settled the question, for now. The line told everyone where slavery could and could not spread in the Louisiana Purchase land. Most of that land lay north of the line, so in the long run slavery was shut out of much of it.
  • It only postponed the problem. Congress had agreed that it could make rules about slavery in the western lands, and the sections had learned how bitterly they disagreed. Thomas Jefferson, by then retired, wrote in April 1820 that the question, "like a fire bell in the night, awakened and filled me with terror." He saw it as a warning for the Union.

The deal held for about thirty years. New arguments came later, with Texas, the war with Mexico, and the Compromise of 1850, covered in other lessons.

Change and continuity: 1809 and 1820

📅 1809

Seventeen states. Slavery was legal in the South. The main national action on slavery itself was the ban on bringing in enslaved people from abroad, from 1 January 1808. The Louisiana Purchase land was new, and no rule said where slavery could go there.

📅 1820

Twenty-two states, then 24 with Maine and Missouri. Congress had fought over whether slavery should spread, and had drawn a line across the western lands. Slavery was still legal in the South, and the sections were openly divided.

What changed, and what stayed the same? Slavery was a national political crisis in 1820, which it had not been in 1809. But slavery itself was just as legal in the South, and the Constitution had not changed.

Common mistakes

  • Saying the Compromise ended slavery in the North or banned it everywhere. It banned it only in the Louisiana Purchase land north of the line (apart from Missouri).
  • Saying Missouri was a free state. It was a slave state. Maine was the free state.
  • Mixing up the line with the 1850 deal. The 36°30′ line belongs to 1820.
  • Saying the crisis was only about slavery. Many arguments were about the balance of power in the Senate.

Exam-style question

This is a Paper 2 Section B (a) question. You need two ways, and each one must compare BOTH sides, using specific facts about each period. One way alone cannot score more than half marks.

Explain TWO ways in which the position of slavery in national politics in 1820 was different from its position in 1809. [6 marks]

(In 1809 there were 17 states, and Congress had banned the import of enslaved people from abroad from 1 January 1808.)

Model answer

One difference is how much slavery divided Congress. In 1809 the national government had mainly dealt with the slave trade, banning imports from abroad from 1808, and there was no great fight over where slavery could spread. By 1820 Tallmadge's amendment of 1819 had split the House, which backed restrictions on Missouri, from the Senate, which refused, and the argument over Missouri had become a major national crisis.

A second difference is the western land. In 1809 the Louisiana Purchase territory was new and no rule said where slavery could go there. By 1820 the Missouri Compromise had drawn the 36°30′ line, banning slavery in the rest of the territory north of it, while Missouri joined as a slave state to balance free Maine.

What lifts it to the top level: two different differences, each with a precise fact about 1809 and about 1820.

Exam tip

Name the fact for each date in the same paragraph. Writing "In 1809 ... whereas by 1820 ..." for each way keeps both sides in view, which is what Level 3 needs.

Recap

  • By 1819 there were 11 free and 11 slave states, and the equal number of senators protected the South.
  • Missouri's request to join as a slave state led to the Tallmadge Amendment and a deadlock between the House and the Senate.
  • The Missouri Compromise (1820): Missouri slave, Maine free, and slavery banned north of the 36°30′ line in the rest of the Louisiana Purchase land.
  • It kept the balance and calmed the crisis, but it only postponed the argument. Jefferson called the question "a fire bell in the night".
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