The 23 South Seattle in 1975 was a very basic route between downtown Seattle and Georgetown. The 1975 schedule and route map show 30 minute headways throughout the day with a couple of extra peak hour trips for riders headed to or from the industrial areas along Airport Way and the residential area in Georgetown. The 23 South Seattle route map from 1975 is very similar to the routing of today’s Metro route 124 between Georgetown and downtown Seattle. The main differences are that the 23 served Georgetown via a Flora Avenue/Carleton Avenue loop and that the 23 entered and exited downtown Seattle via Dearborn/Airport Way (perhaps to connect the Atlantic bus base with downtown) instead of via Holgate/6th Avenue.
Today, Flora Avenue is a very quiet neighborhood street and the buses that serve Georgetown (Metro routes 60 and 124) operate one block over on Ellis Avenue. A few years ago I was in Georgetown and I noticed that there still are still some ghostly remnants of curb paint along Flora Avenue where the 23 South Seattle bus stops were once located.