The St. Charles Streetcar line is a historic streetcar line in New Orleans, Louisiana. It is the oldest continuously operating streetcar line in the world, as it has been in operation since 1835. It is operated by the New Orleans Regional Transit Authority (RTA). Officially the St. Charles Streetcar line is internally designated as Route 12, and it runs along its namesake street, St. Charles Avenue. It is the busiest route in the RTA system as it is heavily used by local commuters and tourists. On most RTA maps and publications, it is denoted in green, which is also the color of the streetcars on this line.