National Airlines - June, 1978

A great timetable from National Airlines.

https://twitter.com/AvGeek71/status/1116441249924427779

Allegheny Airlines - October, 1978

Allegheny Airlines introduce jet service in the October, 1978 timetable.

https://twitter.com/AvGeek71/status/1024316796298518528

Hughes Airwest - January, 1978

There are two good resources for those who wish to learn more about Hughes Airwest.  As usual, Airliners.net has a good thread here, and here's an excellent tribute website.  Interestingly, Hughes is now a part of Delta Air Lines, via Northwest and Republic.