Hot rods are typically American cars with large engines modified for linear speed. Nobody knows for sure the origin of the term "hot rod." One explanation is that the term is a contraction of "hot roadster," meaning a roadster that was modified for speed. Open roadsters were the cars of choice to modify because they were light. Hot Rod may also refer to the connecting rods, cam, or pushrods inside the engine or to the exposed frame rails of such an automobile. It has also been noted that burning out the connecting rod bearings was a very common failure mode for souped up four-cylinder Fords, particularly the Model T, and "hot rod" could refer to that phenomenon. It was adopted in the 1930s or 1940s as the name of a car that had been "hopped up" by modifying the engine in various ways to achieve higher performance.

The term can also apply to other items that are "souped up" for a particular purpose, such as "hot-rodded amplifier".

Late 1930s-1950s early days

The term seems first to have appeared in the late 1930s in southern California, where people would race their modified cars on the vast, empty dry lake beds northeast of Los Angeles under the rules of the Southern California Timing Association. The activity increased in popularity after World War II, particularly in California, due to returning soldiers, many of whom had been given technical training in the service. The original hot rods were old cars (most often Fords, typically Model Ts, Model As 1928-31, 1932-34 Model Bs, or V-8s) that had been modified to reduce weight and improve aerodynamics. Typical modifications were removal of convertible tops, hood, bumpers, windshields, and/or fenders); lowering the chassis; and modifying the engine by tuning and/or replacing with a more powerful type. Wheels and tires were changed for improved traction and handling. "Hot Rod" was sometimes a term used in the 1950s as a derogatory term for any car that did not fit into the mainstream. Hot rodder's modifications were considered to improve the appearance as well, leading to show cars in the 1960s replicating these same modifications along with a distinctive paint job.

Post WWII origins of organized rodding

thumb|right|1949 Mercury thumb|Ford Popular thumb|right| Rodded prewar British Rover 10 After World War II there were many small military airports throughout the country that were either abandoned or very rarely used that allowed Hot Rodders across the country to race on marked courses. Originally Drag Racing had tracks that may have been as long as one mile or more, and included up to four lanes of racing at the same time. As hot rodding became more popular in the 1950s, magazines and associations catering to Hot Rodders were started. As Hot Rodders began to race on the street in addition to drag strips, a need arose for an organization to promote the images of Hot Rodders. Hot rodders including Wally Parks created the National Hot Rod Association (NHRA) to bring racing off the streets and onto the tracks. They created rules based on safety and entertainment, and allowed Hot Rodders of any caliber the ability to race. The annual California Hot Rod Reunion and National Hot Rod Reunion are held to honor pioneers in the sport. The Wally Parks NHRA Motorsports Museum houses the roots of hot rodding.