The Pontchartrain Railroad was one of the first lines completed in the United States. First opening in 1831, and remaining opened uninterrupted for over 100 years, it ran the five-mile length of Elysian Fields Avenue, running from the river in the Marigny to Lake Pontchartrain in Milneburg. Initially, service was only available by horse-drawn omni-buses, until the first steam engine arrived in 1832. The omni-buses remained on the line until at least the 1860s, becoming less frequent as steam engines became more reliable. The infamous, sooty exhaust of the steam engine running this line inspired the name "Smoky Mary". The railroad transported both passengers and goods. Passengers reminisced exiting the train in Milneburg with a thick layer of black soot on their clothes. The railroad helped promote the early boom of Milneburg, which evolved from an industrial port to a popular resort.