Expansion to the Pacific
Political and economic motives lead to territorial expansion across the width of the continent all the way to the Pacific Ocean in the first half of the 19th century.
I Can Statements
- I can explain what Manifest Destiny was and why Americans believed in it.
- I can explain why people moved west (land, money, and trade).
- I can identify and locate the major lands the U.S. gained (1803–1853).
- I can describe how the U.S. expanded from the Atlantic to the Pacific Ocean.
Flip-Card Vocabulary
Click each card to flip it. The back shows the definition plus the cause, effect, and why it matters. Flip a card and tap Mark as mastered once you know it cold.
Westward Expansion
Westward Expansion
The movement of Americans west from the early 1800s to the Pacific Ocean to gain land, resources, and opportunity.
Why it matters: Increased the size of the U.S. and changed its economy and population.
Manifest Destiny
Manifest Destiny
The belief that Americans were meant to expand west across North America in the 1800s.
Why it matters: Justified expansion, even when it harmed Native Americans and Mexicans who already lived on the lands.
Louisiana Purchase
Louisiana Purchase
In 1803, President Thomas Jefferson bought land from France west of the Mississippi River for $15 million.
Cause: The U.S. wanted control of New Orleans and the Mississippi River for trade routes and defense.
Effect: The country doubled in size.
Why it matters: Opened land for exploration and settlement.
Florida Cession
Florida Cession
In 1819, the U.S. gained Florida from Spain through the Adams-Onís Treaty.
Cause: Runaway enslaved people fled to Florida where Native groups like the Seminole protected them, and Spain could not control the area. President Andrew Jackson used military force to pressure Spain.
Effect: Spain gave Florida to the U.S., which agreed to pay $5 million and set clear boundaries.
Why it matters: Showed how the U.S. used both military pressure and diplomacy to gain land.
Oregon Territory
Oregon Territory
Land in the Northwest claimed by both the U.S. and Britain until 1846.
Cause: Both nations wanted the land.
Effect: Divided at the 49th parallel and led to increased migration by pioneers seeking farmland.
Why it matters: Prevented a third war with Britain.
Texas Annexation
Texas Annexation
In 1845, the United States added Texas, which had been an independent country after breaking away from Mexico in 1836.
Cause: American settlers in Texas wanted to join the U.S., and the U.S. wanted more land and slave states.
Effect: Mexico refused to recognize Texas as independent and tensions rose.
Why it matters: Directly led to war with Mexico.
Mexican Cession
Mexican Cession
Land in the Southwest (including California, Nevada, Utah, and parts of several other states) that Mexico gave to the United States in 1848 after losing the Mexican American War.
Cause: Mexico was defeated in the war.
Effect: The U.S. gained about 500,000 square miles of land.
Details: The U.S. paid $15 million in the Treaty of Guadalupe Hidalgo to make the land transfer official.
Why it matters: Greatly expanded the U.S. and raised major questions about whether slavery would be allowed in the new territories.
Gadsden Purchase
Gadsden Purchase
In 1853, the United States bought a strip of land from Mexico in present-day southern Arizona and New Mexico.
Cause: The U.S. wanted flat land for a southern transcontinental railroad route.
Effect: The southern border of the continental U.S. was finalized.
Details: The U.S. paid $10 million for about 30,000 square miles. Named after James Gadsden, who negotiated it.
Why it matters: Marked the last major land acquisition in the lower 48 states and supported transportation growth.
Matching Practice
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Matching Practice
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Multiple-Choice Practice
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Multiple Choice
Westward Expansion refers to: