Rick: President Polk had wanted Baja California to become a part of the United States under the Treaty of Guadalupe Hidalgo, but also told his emissary Nicholas Trist that failure to get it wouldn’t be a deal-breaker in his negotiations with Mexico. I remember reading somewhere years ago that Mexican spies had intercepted correspondence between Trist and the White House, which is why they were so adamant about holding on to Baja: The Mexicans knew the United States didn’t consider it the sine qua non of a peace settlement. At any rate, it’s one of the great missed opportunities of American history–a big chunk of land that might have been ours under different circumstances and, it’s worth adding, a better georgraphical border with Mexico, certainly from the standpoint of preventing illegal immigration. Much better to have the Colorado River as a barrier than a line in the sand north of Tijuana.