At that time, Azerbaijan was part of the Soviet Union until the end of the Soviet Union in 1991. The Baku Metro has the features found in most other ex-Soviet metro systems. These include very deep metro stations, and detailed decorations that blend traditional Azerbaijani national designs with Soviet ideology. The metro system has three lines and has 38.1 kilometers of double railway tracks with 26 stations, all of which is underground. It is run by the "Bakı Metropoliteni". In 2015, it carried 222.0 million passengers, which means an average ridership of approximately 608,200 passengers each day.