The Beijing Subway is a rapid transit rail network that serves the urban and suburban districts of Beijing municipality. The subway's first line opened in 1971, and the network now has 13 lines, 172 stations and 336 km (209 mi) of tracks in operation. It is the oldest subway in mainland China, and the second in length and ridership after the Shanghai Metro. On April 30, 2010, the subway delivered a record 6.4 million rides. On December 30, 2010, Lines 15, Changping, Fangshan, Yizhuang and Daxing opened for operation. Despite this rapid expansion, the existing network cannot adequately meet the city's mass transit needs and extensive expansion plans call for over 700 km (430 mi) of track in operation by 2015 and 1,000 km (620 mi) by 2020. The Chinese government's ¥4 trillion economic stimulus package has accelerated subway construction. The network is set to reach 420 km (260 mi) by 2012.