<human>:  Why did the USA invade Mexico?
<bot>: The USA invaded Mexico in 1846, as part of the Mexican-American War. The United States had been involved in a dispute with Mexico over the boundary between the two countries. The U.S. wanted to take control of the land in the Mexican state of Texas, which Mexico claimed as its own. Mexico refused to accept this, and the U.S. declared war on Mexico in 1846.