The Loop is the name of the 2 miles of elevated track that circle downtown Chicago and was completed in October 1897 as a way to bring the elevated trains of four different railroads into downtown Chicago from their original terminals on the fringes of the city (these terminals were kept for service that exceeded the capacity of the loop with the last one closing in 1950). Today four of the eight Chicago 'L' lines terminate in the loop by reversing through it, never leaving revenue service or changing crews while simply changing the destination signs from loop to the respective terminuses between the stop before the loop and the first stop in the loop on inbound trains. The Orange, Pink, and Purple Line Express (Rush Hours Only) trains use the inner track going clockwise while Brown Line trains use the outer, counterclockwise track. Green Line trains are through routed via the eastern and northern sides of the loop. Red and Blue Line trains each travel underneath downtown in subway tunnels, the Yellow Line is just a shuttle. There are important track junctions at the NW (tower 18) and SE (tower 12) corners of the loop. The NW corner is a four-way junction where the Green and Pink Lines enter from the west and brown and purple lines from the north. The SE corner is simpler with Green and Orange Line trains entering from the south. The loop was originally built with 11 stations: 3 stations on each of its four quadrants except the northern side with just 2. Today there are 9 stations with two new stops opening in the 1990s each combining two of the original ones. In the early years each station was divided into four separate (two on each side platform) fare control areas because transfers weren't honored between the different railroads. Regular service has existed to only run in circles around the loop, such as from 1969 to 1977 when the Loop Shuttle Line operated with two trains making continuous circuits on the inner loop.