May 1927 map showing the East Bay Electric Lines and the Key System commuter trains, produced as part of a report on the then-proposed Transbay Bridge. The map incorrectly identifies the Ellsworth Line as being part of the Key Route system; it was in fact part of the East Bay Electric Lines.
City of San Francisco
<a rel="nofollow" class="external text" href="https://www.flickr.com/photos/walkingsf/4421366154/">Suburban Lines of the Southern Pacific Co and Key System Transit Co to Accompany Report on Transbay Bridge (1927)</a>