The long-awaited extension of the No. 7 train to the far West Side of Manhattan will open the afternoon of Sep. 13, the MTA said Thursday.

The first train to leave the brand-new 34th Street-Hudson Yards station on 11th Avenue will depart at 1:07 p.m., Trip Planner shows on the MTA website. The first to head toward that new station will leave at 12:26 p.m. from the Main Street-Flushing stop.

The city-funded, $2.4 billion station formally opens at 1 p.m. that day, according to the MTA. It is a 1.5-mile extension from Times Square.

It will serve new apartments, offices, restaurants, and stores in the Hudson Yards area on the far West Side.

"The opening of the extension is a real boon to the far West Side, and opens up many new travel options coming and going to the area," said riders' advocate and MTA board member Andrew Albert.

"This includes travelers to the Javits Center, the new offices, and apartments already open or coming to the area. It's always wonderful when New York's transit system expands."

The riders' group 7 Train Blues was glad the opening was almost here.

"We're excited to see progress and hope to have transit continue in a positive direction," said organizer Hayes Peter Mauro. "Including extensions, improvements, and proper maintenance."

One challenge has been installing the transit system's first two incline elevators. The new station is 80 feet under the ground -- but still nowhere as deep as the 191st station on the 1 train, which is 180 feet down. The last extension of the subway system was in 1989. The MTA added three new stations-- 21st Street-Queensbridge, Roosevelt Island, and Lexington Avenue-63rd Street.