Soon after Southwest entered MDW and it was still very much an outstation, the airline had a promotion where any 5-leg one-way (direct or plane change) was a fixed price, might have been $49. This would have been maybe 1987. One of my colleagues in graduate school used that to do something along the lines of MDW-STL-HOU-ELP-LAS-OAK over about 10-11 hours to go visit friends in the Bay Area over Spring Break.