The northern part of the Louisiana Purchase, basically everything north of OTL St Louis at a minimum and west of there (draw a line due west to the Sierra Nevada mountains from there) and south of the US-Canada border has essentially zero white settlements. Assuming it remains Spanish territory you'll still have American mountain men going through there for hunting/trapping and settlers will follow them. Sure we know now there are silver and gold deposits in this area, but back then not at all. IMHO you'd see the same sort of infiltration of American settlers in to that space you saw in Texas, only with even fewer Spanish/Mexican folks living there a rebellion against Spain or simply the US claiming it and offering to pay some nominal fee. The UK can't really make much of a claim and make it stick, in the first half of the 19th century settlement settlement in Canada west of the Great Lakes was essentially nil except for Hudson's Bay waaay north and that was trading posts.
I would expect you'd see a more of less US-Canada like like today, a US-Spain line somewhere south of St Louis extending to the California-Nevada border, and the US Pacific coast being Oregon and Washington. by 1840 or so. After that, anything is possible. The US, if it does not get free transit through New Orleans may get grabby, and th California revolt may or may not happen... Texas, Arizona, and New Mexico may stay Mexican, or not.