Apologies if it's been done before. WI President Polk has his fatal illness a couple of years early, and dies as Winfield Scott enters Mexico City. George M Dallas is President.
What next? I gather Dallas was a strong annexationist. While "all Mexico" is almost certainly a non-runner, could the US end up with significantly more territory than OTL, and if so what might the butterflies be? If Coahuila becomes part of Texas (iirc they had been united under Mexican rule) does that state have to accept a northern border at the 32nd parallel, as Henry Clay proposed? And/or if Baja California becomes American, would its northern boundary be the same as today's, or might places like Los Angeles be included in a separate State or Territory of Lower California, rather than in CA?
And what of Mr Dallas? Can he get an elected term in 1848? I gather he had made himself unpopular at home by his vote on a tariff bill, but patronage might repair some of that. And if he can't get the 1848 nomination, might he have a chance to come back in 1852? And would it greatly matter?
Thoughts?