As they said, the Wikipedia page for the airport you want is probably you best bet. You can also verify the destination using flightradar24 and choose the airport and click routes.

For example, here are the routes that fly out of Alaska Airlines' hub Seattle-Tacoma Airport (click "Show all routes" on the top right of the map to see the lines). Once you click on a destination, you'll see the times and airlines that serve said destination from Seattle.