Until today I had always thought of WKRP as a 70s sitcom. But it actually aired more in the 80s: one and a half seasons in the 70s, two and a half seasons in the 80s. aired from September 1978 to April 1982

The first episode was in September 1978 and the last episode was in 1982. Like Three's Company, it spanned both the 70s and 80s.

It's the same for "Taxi", often considered a '70s sitcom really had more episodes made in the '80s - from 1978 - 1983.