James Knox Polk, a Jackson protégé known as "Young Hickory."

1833 map of Oregon Territory.

1846 map of Oregon Country, extending southward to California.

An allegorical painting from 1872. The author of a travel guide to the Pacific Coast commissioned this painting. The female figure was an allegory of Liberty—a popular iconic representation at the time—who wears the Star of Empire. She leads the white settlers, along with their transportation and communications technology (the railroad and telegraph cables) and their racial and intellectual enlightenment, into the West, as Native Americans, buffalo, and other animals retreat before her.

Lithograph of a political cartoon. Published in New York by James Baillie, 1844. From the Prints and Photographs Division, Library of Congress.