expansionism

United States history

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July 16, 2026

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Expansionism in United States history refers to the belief and practice of territorial expansion across the North American continent and beyond. This ideology, often termed Manifest Destiny, suggested that the United States was divinely ordained to spread its democratic ideals and institutions.1

This expansion involved acquiring territories through purchase, treaties, and war, notably the Louisiana Purchase, annexation of Texas, and the Mexican-American War. This process often led to the displacement and removal of Indigenous peoples from their ancestral lands, such as the Trail of Tears. In the late 19th century, expansionism re-emerged as a "New Manifest Destiny," influencing foreign policy through actions like the Spanish-American War and the annexation of Hawaii. This expansion was driven by economic interests, a desire for markets, and a belief in American exceptionalism.1234

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United States
Expansionism and political crisis at midcentury
Throughout the 19th century, eastern settlers kept spilling over into the Mississippi valley and beyond, pushing the frontier farther westward. The Louisiana Purchase territory offered ample room to pioneers and those who came after. American wanderlust, however, was not…
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Throughout the 19th century, eastern settlers kept spilling over into the Mississippi valley and beyond, pushing the frontier farther westward. The Louisiana Purchase territory offered ample room to pioneers and those who came after. American wanderlust, however, was not…
Read More

Today in History—March 30
Why the U.S. Bought Alaska—When No One Else Wanted It
…and Seward, a proponent of American expansion, smelled a bargain. He defended the purchase before the U.S. Senate, then wined and dined critics and undecided congressmen at his Washington home, waxing poetic about the beauty of Russian Alaska.
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…and Seward, a proponent of American expansion, smelled a bargain. He defended the purchase before the U.S. Senate, then wined and dined critics and undecided congressmen at his Washington home, waxing poetic about the beauty of Russian Alaska.
Read More