Film about WWI - Need Footage of Boxcars

I am working on a film about WWI, and I am interested in acquiring footage (if available) or photographs of boxcars that would have traveled between Washington, DC and Baltimore during that era. Does anyone have any suggestions? Buzzwords would also be helpful.

Any railroad's boxcars could have travelled between those two cities.

Here's some sources for footage:

http://www.pentrex.com/

http://www.greenfrog.com/

-otto-

You might also try http://www.archive.org.

Tom