Multiple choice Which of the following states of the U.S.A. once belonged to Mexico? California and Texas Kansas and Kentucky New Mexico and Arkansas Rhode Island and Hawaii Reveal answer Fill a bubble to check yourself A Correct answer Explanation California and Texas were part of Mexico before the Mexican-American War (1846-1848) and were ceded to the United States through the Treaty of Guadalupe Hidalgo in 1848. The other options were never Mexican territory.