What was the first 2-8-4 steam locomotive?
2-8-4
The first American 2-8-4s were built for the Boston and Albany Railroad in 1925 by Lima Locomotive Works. The railroad's route across the Berkshire mountains was a substantial test for the new locomotives and, as a result, the name Berkshire was adopted for the locomotive type.
4-2-4T
The first eight known 4-2-4 locomotives entered service on the broad gauge Bristol and Exeter Railway in 1853 and 1854, numbered in the range from 39 to 46. They had diameter flangeless driving wheels, supported by leading and trailing two-axle bogies. The water was carried in both well- and back-tanks. Two more engines were built in 1859 and 1862, but with much smaller diameter driving wheels.
Between 1869 and 1873, new locomotives were built to replace four of the original diameter driving wheeled engines, re-using the engine numbers of the locomotives being replaced. These four replacement engines had slightly smaller diameter driving wheels.