Expansion and Manifest Destiny

History of the USA · Expansion and sectional conflict. The idea in plain words, the rules to remember, the mistake to avoid and a worked example, written and checked by Mega Lecture.

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The idea

Between 1803 and 1853 the United States grew from the Mississippi to the Pacific. The Louisiana Purchase (1803) bought the land between the Mississippi and the Rocky Mountains from France and roughly doubled the country. Florida came from Spain by the treaty of 1819.

The Monroe Doctrine (1823) told Europe that the Americas were closed to new colonies, and promised that the United States would stay out of European quarrels.

In the 1840s Manifest Destiny, the belief that Americans were meant to spread across the continent, drove the annexation of Texas, the Oregon settlement with Britain and the war with Mexico. Every new territory reopened one question: would it be slave or free?

Rules to remember

Common mistake

The Monroe Doctrine did not order Europe to give up the colonies it already held. It opposed new colonisation and interference with the independent states of the Americas.

Worked example

Why did territorial gains in the 1840s sharpen the quarrel between North and South?

  1. New land would become territories and then states, each with two senators.
  2. Whether those states allowed slavery would decide the balance of power in Congress.
  3. So Northerners opposed annexing Texas as a slave state, and the Wilmot Proviso (1846) tried, without success, to ban slavery in any land taken from Mexico.

Answer: Expansion forced Congress to decide on slavery in each new territory, which turned growth into a sectional contest.

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