Seoul has a well developed transportation network. Its system dates back to the era of the Korean Empire, when the first streetcar lines were laid and a railroad linking Seoul and Incheon was completed. Seoul's most important streetcar line ran along Jongno until it was replaced by Line 1 of the subway system in the early 1970s. Other notable streets in downtown Seoul include Euljiro, Teheranno, Sejongno, Chungmuro, Yulgongno, and Toegyero. There are nine major subway lines stretching for more than , with one additional line planned. , 25% of the population has a commute time of an hour or longer.