Here are links to four Delano photos in the Smithsonian's FSA/OWI
collection showing cars being chalked. C&NW Proviso Yard, c. 1942-43

The location appears to be at the top of the hump.

http://memory.loc.gov/pnp/fsa/8d23000/8d23700/8d23722u.tif

http://memory.loc.gov/pnp/fsa/8d23000/8d23700/8d23723u.tif

http://memory.loc.gov/pnp/fsa/8d23000/8d23700/8d23724u.tif

http://memory.loc.gov/pnp/fsa/8d23000/8d23700/8d23725u.tif

One photo is captioned: "Chicago, Illinois. Car checker writing
instructions in chalk for special handling of cars going over the
hump at a Chicago and Northwestern Railroad yard."

And for good measure, here's a car inspector eyeing a Mather boxcar.

http://memory.loc.gov/pnp/fsa/8d23000/8d23700/8d23726u.tif


Jack Mullen