The vehicle identification numbers on automobiles made before 1951 vary in length depending on the manufacturer. All vehicles manufactured in the United States after 1954 have VINs. Vehicles made after 1981 have standardized 17-character VINs.
Antique cars have car number plates, or serial numbers, instead of VINs. The serial number indicates the manufacturing location, the month of manufacturing and the assembly line series from which the car came. The length of the serial number varies between manufacturers.
As of 2015, the National Highway Traffic Safety Administration has standardized the assignment of VINs, requiring that each vehicle have a 17-character VIN made of both numbers and letters. Like classic car serial numbers, these VINs provide information about the car's manufacture date and location, the chassis and model of the vehicle, the engine and transmission type, and a "check digit." The check digit exists for redundancy and to identify errors in the numbering sequence.