Pennsylvania

They only run on steam a few times a year. It's actually a small regional freight railroad that does "last mile" transfers of smaller numbers of cars that the big railroads don't want to handle. They started the tourist trips as they accumulated old passenger cars and as a sideline to the meat and potatoes but it's become a going concern. They sell out in the fall and the steam runs fill first (at a 50% per seat premium for the pleasure). I think Strasburg is all steam which is cool and has been around alot longer.