Name one state that borders Mexico.

Why this is the answer

Four states touch Mexico: California, Arizona, New Mexico and Texas. Naming any one of them passes. The border they share runs about 1,900 miles and is one of the busiest international borders in the world. The line was drawn in stages during the 1800s, and the story behind it doubles as review for other questions. Texas was part of Mexico until 1836, when it won its independence and spent the next nine years as a country of its own. In 1845 it joined the United States as the 28th state. Mexico still wanted Texas back and also claimed a wide stretch of the Southwest between the Rocky Mountains and the Pacific, and in 1846 the two countries went to war. That conflict, the Mexican-American War, is one of the accepted answers to the question asking for a war the United States fought in the 1800s. The United States won in 1848. In the treaty that followed, Mexico accepted that Texas was part of the United States and sold the land it claimed in the Southwest. That land later became California, Nevada and Utah, along with parts of Arizona, Colorado, New Mexico and Wyoming. The last piece came with the Gadsden Purchase of 1853, when the United States paid $10 million for land it needed to extend the southern railroad; that land is part of Arizona and New Mexico today. This history also explains the wrong answers that sound right. Nevada and Colorado both include land Mexico agreed to sell after the war, so they feel tied to the border, but neither touches it now. Louisiana can tempt you because it is a southern state, yet its name points to a different deal entirely, the Louisiana Territory that the United States bought from France in 1803. To keep the four in order, travel the border from the Pacific eastward: California, Arizona, New Mexico, Texas. Two of those four, Arizona and New Mexico, owe part of their land to that 1853 railroad purchase.