The U.S. should NOT declare war on Mexico because 1. Mexico and the U.S have very close economic ties and the U.S. is Mexico's largest trading partner. 2. The U.S. gets a lot of people that are, citizens or no, working. The immigrants kind of help the U.S. from going into another Great Depression. 3. Besides the fact that the Mexican government helped during 9/11 and opted not to join the War on Terror.