Who invented the steam locomotive (1830)?

Answer 1

Credit for the first fully functional steam locomotive goes to Richard Trevithick in the UK - although some prototypes had been built by prior inventors such as William Murdoch and John Fitch but there were not really workable due to limitations on the pressure that could be contained in their boilers. Richard Trevithick made the necessary breakthrough in designing and building an effective high-pressure boiler that could be used to power a locomotive.
The first full-scale working railway steam locomotive, called the 'Puffing Devil,' was built by Richard Trevithick.

In the USA the B&O Railroad's Tom Thumb, which went into service in 1830, was designed and built by Peter Cooper and was the first US-built locomotive to run in America, although it was intended as a demonstration of the potential of steam traction, rather than as a revenue-earning locomotive.