As a result of that war, which major western territory was annexed by the United States?

• A. Oregon
• B. California
• C. Texas
• D. New Mexico

Answer: (B)

After the Mexican-American War, the United States expanded its western lands through the Treaty of Guadalupe Hidalgo in 1848. California was the major western territory acquired in this outcome, ceded by Mexico and quickly becoming a focal point of westward growth and economic opportunity. The Gold Rush soon followed, accelerating settlement and statehood for California in 1850, which underscored why this region is seen as the defining territorial gain from that conflict. Oregon had already come into U.S. hands through earlier arrangements with Britain, Texas had joined the United States before the war, and New Mexico was part of the broader Mexican cession; California stands out as the standout territory specifically linked to the war’s result.