It's official: The 7 train extension to 34 Street-Hudson Yards will open to passengers on Sept. 13. 

Passengers will be able to ride the 7 train to the west side shortly around 1 p.m., the MTA said in a tweet on Thursday that announced the opening date. 

RELATED: Pope Francis visit only one of many having city scrambling in September

The project cost $2.4 billion and has been pushed back several times. Construction started in 2007, and former Mayor Michael Bloomberg took a ceremonial first ride in December 2013. 

The opening comes just in time for Pope Francis' visit and the UN General Assembly in late September. The MTA is preparing for more riders as the streets will be clogged up. 

RELATED: MTA preparing to open 7 train to 34 Street-Hudson Yards