Locomotive No. 999 is a historic steam locomotive built in 1903 by the American Locomotive Company. It is notable for being one of the first locomotives to reach a speed of 100 miles per hour, achieving this milestone in 1905. The locomotive was designed for passenger service and is a significant example of early 20th-century engineering. Today, Locomotive No. 999 is preserved at the New York State Museum in Albany, New York. It serves as a symbol of innovation in rail transport and is a popular attraction for visitors interested in the history of trains and transportation.