Which U.S. States Were Once Part of Alta California?

The vast territory of Alta California, under Spanish and later Mexican rule, encompassed land that would become several present-day U.S. states. These include:

• California (entirety)
• Nevada (entirety)
• Parts of Arizona
• Parts of Utah
• Parts of Colorado
• Parts of Wyoming

This territory was ceded to the United States following the Mexican-American War (1846–1848) under the Treaty of Guadalupe Hidalgo.