A lot of stuff in cities is gone. Chicago, Milwaukee, Los Angeles used to be full of all kinds of tight cornered local trackage. Theres probably lots of books on the old trackage of all 3 of those and more. For example, google the Milwaukee Beer Line. A Kalmbach book on Modeling Cities and Towns recently came out and has some chapters on stuff like that.
Some of this stuff does still go on, here's a great example:
BNSF runs a local or 2 south of LAX around El Segundo, and I think UP runs one in Torrance that also are probably worth exploring on a map.
