Annexing north Mexico 1800s

[minionofmidas]

Baja California Sur still isn't densely populated, so why not throw that in, too? Mexico didn't even give them statehood until 1974.

Believe it or not the Mexicans were able to keep us Gringos out of southern Baja during the Mexican War, mainly because for us it was a sideshow far removed from any supply lines.  In any case, it was thought to be worthless desert.  What is surprising is that we didn't use the Mexican border between Alta and Baja when it came time for the treaty.  Mainly that was because we weren't certain if San Diego was north or south of that border and we definitely wanted San Diego for its harbor.  However, if we had used the Mexican border between the Californias, Tijuana would be a US city with its suburb of Rosarito Beach being the Mexican border city.

Tijuana wouldn't have existed: it is where it is because of the border.

While it wouldn't be the same, Tijuana most likely would exist as a suburb of San Diego.

Of Rosarito, surely.

What wouldn't exist is National City.

[minionofmidas]

There would have been San Diego suburbs in the area, that's for sure. But no real reason to think that there would have been a city called Tijuana, nor that its core area would have been anywhere near where it is now. Tijuana's one and only reason to exist, at least originally, is the presence of the border. There would have been a Mexican city wherever the border would have passed.

...which would also be spilling north of the border. All the Mexican border cities do. That was the logic I was using. (Tijuana would be where it is even if there were somehow no San Diego... the port got filled in by an earthquake or whatever... it's as much a suburb of LA as of San Diego.)