I don't know of any other inter-city flights. I do remember not to long ago United express used to fly between Baltimore and Washington Dulles, but they don't do that anymore. Now I know that Baltimore is obviously not a part of Washington, D.C., but they are very close to each other. I think the flight was under 50 miles, but I am not totally certain.
God bless through Jesus with lots of love,
God bless through Jesus, Jeff