Probably an event in the early 1960s. I guess that's the 610 in the lead. but can't quite tell.

http://abpr2.railfan.net/abprphoto.cgi? ... tis.VA.jpg

Just a guess, but possibly the 1966 NRHS Convention. I know one of the events was held there. I didn't go since I was only 3 years old at the time!

I suspect this event was earlier than 1966. Note the cap worn by the GI brakeman is the flat-topped kind worn in the late 50s and early 1960s. I'm not sure when they went out, but I believe they were no longer worn by 1966.