Tom Thumb was the first steam locomotive built in America to operate on a common-carrier railroad.
Peter Cooper designed and constructed it in 1829 to persuade the newly formed Baltimore and Ohio Railroad owners to adopt steam engines. It was not meant to be used to generate revenue.
Tom Thumb is best known for taking part in a famous race with a horse-drawn car, which the horse ended up winning after Tom Thumb experienced a mechanical failure. However, the demonstration was successful.
As a result, the railroad committed to using steam locomotion. Subsequently, trials were held the following year to test a working engine.