Flying student standby in 1970 as a high schooler, you went from airline to airline, hopping from city to city to get where you wanted to go. That day I wanted to go from Albuquerque to Spokane. It ended up Continental to Denver, United to Salt Lake...and then my first contacts with two carriers in what is now Delta...
Hughes AirWest on a DC-9 which flew SLC-Great Falls-Kalispell-Spokane.
When I flew home it was a Hughes AirWest propeller plane from Ephrata, WA to Seattle and Western Airlines Boeing 720 SEA-LAX. All Skyteam!
The Western student standby desk at LAX (separate counter with its own sign) recommended I go to TWA to standby for the next flight. I walked across the huge parking lot at LAX and got on a Boeing 707 LAX-TUS-ABQ.