That's illogical. For example, CO flies to STL, but you can't fly STL to DFW non-stop on CO.

Since STL is an AA hub, the non-stops are to most AA cities (AA timetable will provide them). For the other airlines, it's just the hubs (which is a lot of cities for WN). If you don't care which airline serves which route, then all you need is the AA schedule.