Mileage Plus members who fly three qualifying roundtrips on United, United Express or Ted by June 15 will earn a free economy-class ticket anywhere United flies in the 48 contiguous United States. Passengers who purchase six qualifying trips will earn another free roundtrip ticket in first class.

Qualifying economy-class travel will not include Saturday night stays. Participants must register for this offer by April 15. To register, go to http://www.united.com or call (800) 541-4184.