This takes some time to research. For example, one of the oldest US airlines is HA. In a 1950 timetable, the airline flew the same Honolulu to Lihue route as they do today multiple times a day with different flight numbers. If one goes further back, HA operated the Honolulu to Kauai route in 1932 as Inter-Island Airways, without a flight number and landing at a different airport on Kauai.
Perhaps the OP could be a bit more specific with the request?