America in Color 1939-1943 ~ Friday, July 30, 2010
A few years ago the Library of Congress put together a show of color photographs collected by the government to document the depression and domestic effects of WWII.
You can see it online at the L.O.C. site, or (imho better presented) at this Denver Post Photoblog site (and note that blogger shrunk my samples when I posted them, so you can see them much better on the original sites).
The collection has lots of great pictures from the "classic railroading era" that lots of us like to model--in color, which we rarely get to see. I didn't see anything specifically trolleyish, but there are good shots of urban scenery, like this:
and more of rural life
and plenty of railroads, and classic modelable industries
I've mostly posted scenic examples, but there are lots and lots of pictures of people--at work, out and about, kids playing, etc.
There's lots more there--check it out!