What treaty established the Oregon territory boundary between the U.S. and England?

The Oregon Treaty of 1846 is the correct answer because it specifically addressed the issues surrounding the boundary of the Oregon Territory between the United States and Britain. The treaty established the 49th parallel as the boundary, extending to the Pacific Ocean. This agreement resolved the long-standing dispute over the Oregon Territory, which both nations claimed due to earlier explorations and settlements.

Prior to this treaty, various treaties had been signed, but none accurately delineated the boundary in question. The Adams-Onís Treaty involved Spain and was focused on territory in the Gulf Coast and the western U.S. The Treaty of Guadalupe-Hidalgo ended the Mexican-American War and resulted in land gains for the U.S. The Treaty of Paris, particularly the one in 1783, concluded the American Revolutionary War, establishing U.S. independence but not relating specifically to the Oregon Territory. Thus, the Oregon Treaty of 1846 stands out as the pivotal agreement that defined the U.S.-British boundary in the Pacific Northwest.