Sent my way by Dennis, who says:

Today’s offering is spurred by news of a new Muni map showing frequency of service. Here’s the one I created for personal amusement in 1982. As you can see, the technology was a bit more primitive: Rapidograph technical pens, a calligraphy pen, and crepe-paper tape on tracing paper.  The rest of the page (of a visitors guide I made for friends) was typewritten.

Transit Maps says:

Nice and simple – that’s the way to do it. Just coastline, a few landmarks and route lines which get thicker the more frequent the service is. A quick comparison with the new Muni map reveals that many of the routes still exist in almost identical form some 33 years later.