We often forget that the boundary between the United States and Mexico was not always where it is today. It used to be seven hundred miles farther north, following what is now the state line between Oregon and California and running east to Wyoming before zagging southeast to Louisiana. Originally home to the indigenous peoples of the region, much of this land was Spanish and then Mexican territory for centuries before becoming what we now think of as the American West.
Spanish colonists and missionaries settled here beginning in 1598. In 1821, Mexico won independence from Spain, and by the…
