When did American expansion begin?

American expansion refers to the territorial growth of the United States over time. The first major period of American expansion occurred in the early 19th century, when the country acquired vast territories in the Louisiana Purchase (1803), the Florida Purchase (1819), and the Mexican-American War (1846-48).

This expansion continued throughout the 19th century with the annexation of Texas (1845), the Oregon Treaty (1846), and the acquisition of Alaska (1867). Subsequently, the United States acquired territories such as Hawaii (1898), Puerto Rico (1898), and Guam (1898) as a result of the Spanish-American War.