The Democrats were in power in 1940, so the dam on the Colorado River was still called Boulder Dam. By 1952, it would be called Hoover Dam again, a name given it in 1930 to honor the U.S. president who was trained as an engineer.
This menu says it was used in a coffee shop car. It has an a la carte side, but the table d’hôte side is mostly blank, awaiting an insert. The one item on the table d’hôte side is the charcoal broiled sirloin steak dinner for $1.75, or about $30 in today’s money.