So I was looking at Arizona the other day and got to wondering about the small strip of land, belonging to Mexico, that separates it from the Gulf of California.
Ports are a big deal. Wars have been (and continue to be) fought over them. So why did the United States not seize that portion of land in the Mexican-American War? I understand the State of Arizona was created after the war but I would have thought ocean access would be desirable and that land taken anyway.
What is now Arizona was considered a vestigial part of Alta California when it was surrendered to the US by Mexico, along with claims to Nuevo Mexico and Texas. Most of the Eastern portion of Alta California was inaccessible, barren and subsequently left to the native populations for the remainder of the 1800's. At the time of California statehood, there was still a pretense of "Indian territory". California had all the ports it needed and at that moment, the Arizona territory had nothing of substance to ship or receive, so the necessity of a port was moot.
When Arizona became a state in 1912, the railroad served the states minimal needs just fine. Most of its resources were consumed within the US, so the need for international waters did not exist.