On this day (13 May) in 1846, the United States Congress approved a declaration of war against Mexico. As a result of this unjustified war of aggression (see here or here, for example), the United States would end up acquiring — “stealing” would be a more accurate term — 500,000 square miles of Mexico or roughly 55% of her territory, including present-day Arizona, California, Nevada, and Utah, as well as portions of New Mexico, Colorado, and Wyoming!