The term refers to the agreement reached between Britain and the United States in 1846, known as the Oregon Treaty, which established the boundary between their territories at the 49th parallel.
Related terms
Manifest Destiny: The belief during the 19th century that it was America's destiny to expand its territory from coast to coast.
Oregon Trail: A historic pioneer trail that stretched over 2,000 miles from Missouri to Oregon, used by settlers traveling westward during the mid-1800s.
Treaty of Guadalupe Hidalgo: The treaty signed in 1848 between Mexico and the United States which ended the Mexican-American War and ceded significant territory to the U.S., including California.