The Terraplén Subway is the oldest and busiest of the 8 Ivalion Metrorail lines in Ivalion County, Califia, Ivalice. It is operated by the Ivalion County Transportation Authority and has 30 stations. It was opened in 1947, with extensions completed in 1954 and 1972. The Terraplén line was originally called simply the "Metrorail" until the first extension to University in 1954. From 1954 until 1968, it was known as the Red Line, adopting its current name in 1968.