The American Civil War, 1840–1877 · THE MAP IN 1840

Map of North America in 1840

A continent of rival claims

North America in 1840: A continent of rival claims. The map shows who held what: The Union, Mexico, 1840–54.

On the ground

• Mexico City claimed the far north, including Alta California and Nuevo México, beyond the Adams–Onís line established by the US–Spanish border treaty of 1819. In fact, Comanche, Apache, Navajo and Ute nations held the region as much as Mexican settlers did.
• The slaveholding Republic of Texas had been independent since 1836. The United States recognized it in 1837; Mexico never did.
• Texas claimed the Rio Grande as its boundary, while Mexico claimed the Nueces. Taylor’s army marched into the disputed strip in March 1846, and the war began there.
• Britain and the United States jointly occupied the Oregon Country west of the Rockies from 1818 until the 49th-parallel treaty of 15 June 1846.

Related maps

• Map of the United States in 1840 AMERICAN CIVIL WAR
• Map of Japan in 1840 MEIJI JAPAN AND POST-SOVIET RUSSIA
• Map of the Industrial Revolution in Europe around 1840 INDUSTRIAL REVOLUTION
• Every map of 1840
• American Civil War maps by year
• American Civil War timeline: every chapter