The extension of the 7 train to Manhattan's Far West Side has been powering an enormous makeover of a neighborhood that once wasn't all that open to transit or business.

A sprawling neighborhood is rising on Manhattan's Far West Side: 28 acres of buildings and green space over a platform covering a rail yard.

Officials say this development would not be possible, or at least as grand, without the opening of a new subway stop a short walk away.

"The extension of the number 7 subway is the game-changer," said Jay Cross, president of Related Hudson Yards. "And I think once it gets open and people get used to riding it and know it's an alternative for them, it's really going to change everyone's perception of coming to the West Side."

The 7 makes its first run into the station at 34th and 11th on Sunday, a milestone for a once-seedy and far-flung neighborhood now on the rise, with 17 million square feet of commercial and residential space under construction at the Hudson Yards development.

"To be able to bring the subway right to the front door, the front door of the Javits Center as well as Hudson Yards and Manhattan West, really says that you have the best public transportation system in the region now in this part of town," Cross said.

The city kept betting on the Far West Side even after plans to build a stadium there crumbled, pouring $2.4 billion into extending the 7 line.

The promise of the Far West Side was enough to convince the city, under Mayor Michael Bloomberg, to fully fund the mile-and-a-half-long extension of the 7. It marks the first time the city has fully paid for a subway extension since the 1950 opening of the 179th Street Jamaica station on the F.

"The city recognized that to get people to live, to work, to play, to dine on the Far West Side, we had to make sure it was no longer far," said Mark Heavey, director of marketing for the MTA.

It's good news for travelers taking Mega or Bolt discount buses, which stop nearby, and for the visitors flocking to the popular High Line.

"Most people come on the High Line and they start downtown and walk uptown. They get here and then they walk back," said Robert Hammond, co-founder of Friends of the High Line. "And I think now, they'll be able to walk north, get on the subway and go wherever else they're going."

And starting Sunday, the 7 is going west.