Yes they did MIA was their South American Gateway. After ORD and SFO I believe it was their largest operation. You could get to most places in the country at least once a day non stop. UA abandoned South America from MIA and cut back to just a handful of Ted flights. UA (as in non TED) metal no longer flies from MIA or FLL these days. There was even a RCC in MIA at one point. AA has always been tops for MIA dominanace but, at one point UA was a close second.