• According to one source, dry van, flatbed, tank, refrigerated and specialized are common trailer types.
•  Flat Rate Central has slightly different classifications: dry van, flatbed, refrigerated, lowboy, step deck, conestoga and specialized.
• One source states there are 5.6 million trailers operating in the US, but the source of this information isn't stated.
• The US Census Bureau collects information on truckers, trucking businesses and the economic impact of trucking but not on trucks/trailers themselves.
• The Bureau of Transportation Statistics does collect information on trailer registrations, but the data is from 2012 as it is only collected every 10 years. The only trailer types offered are commercial trailers, light trailers (farm, car) and house trailers.
• In the US, there were 11.7 million commercial trailers registered. Some state-level data is missing, but Tennessee is actually showing as the most registrations, with 1.39 million. Second is Pennsylvania at 1.1 million and third is California with 1 million.
• Other data sets do not discuss trailers.

Summary of Information

• There is no definitive classification of trailer types, at least in official government-level data.
• Data on US trailer registrations is only collected every ten years, and therefore will not be refreshed until 2022.
• It is possible that examining broader market/industry research on trailer manufacturing may reveal information on the distribution of trailers by type, but this would need to be investigated further.