I'm looking for links to photos of crews using hand signals, no matter the railroad, but preferably in North America. Videos are ok too, there are a ton of promotional films from any number of railroads on Youtube, but watching that many hours of old film is impossible. Do you remember a certain scene? I'm looking for anything prior to handheld radios, if possible.

John, I don't have any ready links to photos for you, but one of my Father's best hand signals (not in the official rule book) was used by yard crews. A simple circular motion rubbing your belly followed by the motion of a fork entering your mouth was a hand signal for "Let's go get some beans" (ie: lunch break). No radio or cell phone required and every body figured it out pretty quickly...

Yes, we also used a circle made under one'as ass while hanging off a boxcar, to let the engineer know to stop and give his helper a chance to go behind a bush...

Try these:

https://www.youtube.com/watch?v=4JensPwtu4s

Night signals about 01:15

Several switching sequences about 12:00 - 13:00

And:

https://www.youtube.com/watch?v=B9VqccMWF-c

Making a joint at 5:00
Signaling from a car roof at 13:30

Have fun.

More stuff...

Still photos of switching hand signals are hard to find because the signals tend to be used rather informally, and in a still photo they tend to just look like random hand movements. However, here's two Jack Delano photos from the WWII era that fill the bill:

you may have to drag thru some films, but look for the promotional films like the Nickel Plate.

When I was growing up in the 1950's and 60s my father commuted on the NYC Harlem Division. On passenger trains, to start after a station stop, the hand signal was one quick vertical wave which I remember well.

I never thought I would see it again but discovered it here at about 2:52 minutes in:

https://www.youtube.com/watch?v=d2jbS0cpq8s

This always strikes me as so different from starts on tourist railroad passenger trains, which are by comparison, so leisurely. When an NYC conductor gave this signal, as you can see, the train started within a few seconds!