Originally Posted by dcpatti

Keep in mind that you're booking travel between BOS-ORF. If there's irrops, mechanical problem, overbooking etc they might (and are perfectly allowed to) reroute you BOS-DCA-ORF.

As far as pricing structure, to the folks who set the fares, BOS-LGA is a more "valuable" service than BOS-ORF regardless of connecting point. People in BOS will pay more to go to NYC than they will pay to go to Norfolk. So they charge more for the fare, even if it theoretically costs them less to operate that flight than it does to operate 2 flights to get you to ORF.