How do you knwo they everlost it?
POD would probably be pre Texas annexation. It is possible that the British too Louisiana, or large parts there of, during the Napoleonic Wars (decisive victory in War of 1812 or directly taken from France). Presumably the US wouldn't try to claim the Oregon Territory because they didn't have Northern Louisiana creating a border with it or a Pacific Coast (Texas was never annexed preventing the Mexican-American War, so California successfully rebelled and became and independent country rather than a part of the US. I would presume Deseret was created therough the samemechanism as those two, with Mormons immigrants declaring independence).