I’ve flown on scheduled flights on common carriers intra-California, intra-Colorado, intra-Florida, intra-Minnesota, intra-Michigan, intra-Pennsylvania, intra-Virginia, intra-New York, intra-Hawaii, intra-Texas, intra-Ohio, intra-North Carolina, intra-Georgia, intra-Wisconsin, intra-Illinois, intra-Nevada. I may even have left out one or two that I have taken. There are intra-Washington flights too.

Mileage runs and the benefits of throwaway ticketing with even mileage tickets have really expanded the horizons.

Update: Massachusetts also has intra-state flights, beside those mentioned elsewhere in this thread.