There's a wide variety of collectible railroad signs, with a few common themes. Signs from the railyards gave instructions to train crews and yard workers, often safety related. On-board signs would indicate dining cars, restrooms, compartment numbers, and other information for passengers. At grade crossings, one could find the classic 'X' shaped railroad crossing signs with embedded cat eye marbles to reflect car headlights at night.

But by far the most colorful and collectible antique railroad signs are the promotional signs - often porcelain - which were featured in depots and stations. These beautiful signs advertised everything from the railroad itself and its latest marketing slogans to specific routes and even mascots.