Thanks. Great thoughts. However, due to American expansionism and the "Manifest Destiny" idea, I think the US may try to take back the territory any time in the future ITTL. Perhaps it tries to do so during the Civil War, if Britain supports the CSA?A classic history I would urge everyone to read is The Fatal Shore by Richard Hughes, detailing the history of the Australian penal colonies. It is truly fascinating and can be the jump off points for numerous TLs.
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Oregon becomes both British and later on, Canadian. And the thrust of American transcontinental ambitions is deflected southward to Southern California, Sonora, Sinaloa and Nayarit.