the US bought the whole thing, because it was pretty much an 'all or nothing' offer, and the US really wanted New Orleans. If Napoleon refused to sell it... I'd imagine the USA would look on disgruntled until word of Napoleon's first abdication came along... and then they'd muster whatever they could and try to capture the town. The rest of the territory wasn't seen as desirable at all, although the US would want all the land west to the Mississippi River, just to have a clear right of passage all the way down it. Later on... who knows? One big question is if the USA takes all of LA east of the Mississippi, and doesn't really claim anything west of the river, who does claim it?