Detroit has a downtown (not much of one, unfortunately), but no uptown that I'm aware of. My mother's hometown of Mt. Carmel, PA, on the other hand, had an uptown but no downtown. Wonder how different places came to use the different terms to refer to the same part of their town, eg, business/shopping/entertainment district - while other places use both, referring to two distinct areas of the city. Suppose the answer's lost in the mists of time....