The Metra Electric District is an electrified commuter rail line owned and operated by Metra which connects Millennium Station, in downtown Chicago, with the city's southern suburbs. As of 2018, it is the fifth busiest of Metra's 11 lines, after the BNSF, UP-NW, UP-N, and UP-W Lines with nearly 7.7 million annual riders. While Metra does not explicitly refer to any of its lines by color, the timetable accents for the Metra Electric District are printed in bright "Panama orange" to reflect the line's origins with the Illinois Central Railroad (IC) and its Panama Limited passenger train. Apart from the spots where its tracks run parallel to other main lines, it is the only Metra line running entirely on dedicated passenger tracks, with no freight trains operating anywhere on the actual route itself. The line is the only one in the Metra system with more than one station in Downtown Chicago, the only line with no stations in fare zone 4, and also has the highest number of stations (49) of any Metra line.

Railway electrification is the use of electric power for the propulsion of rail transport. Electric railways use either electric locomotives, electric multiple units or both. Electricity is typically generated in large and relatively efficient generating stations, transmitted to the railway network and distributed to the trains. Some electric railways have their own dedicated generating stations and transmission lines, but most purchase power from an electric utility. The railway usually provides its own distribution lines, switches, and transformers.