All rail cars in Mexico, the U.S.A. and Canada are listed in the "Equipment Register" and those operating on U.S. railroads must meet the Association of American Railroads (AAR) and federal government construction standards for safety and interlining (movement between railroads), and must be maintained to those standards.
The common freight cars are: box, flat, covered hopper, open top hopper, tank, and gondola, each costing from $40,000 for a standard railcar ordered in quantity, to over $200,000 for a specialized tank car. Special cars include the heavy duty flat, refrigerated box, pneumatic and pressure differential covered hopper, auto rack flat, 90' pole flat, 80' high-cube boxcar. 24' open top ore hopper, and many others.
All railcars are 9.5 feet wide, give or take 10 inches, and range from 24' to 90' in length. Most are 10 to 12 feet high---except for flat cars which are, of course, flat, and gondolas usually have 3' to 4' high sides. Car height is measured from the floors of rail cars, which are 3.5' to 4.5' above the top of the rail.
Most rail cars' load capacities range from 120,000 pounds (some boxcars and special cars for lighter commodities) to 200,000 pounds (most newer cars of all types). Some special tank cars and heavy duty flat cars for moving electrical transformers and equipment carry much more tonnage. The load capacity and empty tare weight is stenciled on the side of every railcar. Normal maximum gross weight (total weight of rail car and its contents) is 263,000 pounds.