WASHINGTON — Google has agreed to invest in an underwater transmission network intended to harvest electricity from wind farms off the mid-Atlantic coast and power 1.9 million homes from Virginia to New York and New Jersey.

Google will buy a 37.5 percent stake in the development stage of the Atlantic Wind Connection project, Rick Needham, director of green business operations at the Internet company, said in a blog post. The project will cost about $5 billion, with Google and project leader Trans-Elect Development Co. each putting up about $200 million initially, according to Trans-Elect.

The network and Google’s involvement will help spur the wind-energy industry in the United States, which has lagged behind China in installing turbines, said Charlie Hodges, a wind industry analyst at Bloomberg New Energy Finance in London. Wind-power investment may reach $202 billion within two decades, according to estimates by the industry group Global Wind Energy Council.

“The North American wind industry hasn’t had any players involved with the motivation and financial heft to really move this market forward,” Hodges said. “Google could play that role.”

Google, based in Mountain View, Calif., and Good Energies, an investor in renewable-energy projects, each will have a 37.5 percent equity stake in the project, said Robert Mitchell, chief executive officer of Trans-Elect of Chevy Chase, Md. Japan’s Marubeni Corp. will own a 15 percent stake, said Daniel Welt, a vice president of development at a Marubeni subsidiary.

The first phase of the project, which the developers aim to complete by early 2016, would run about 150 miles and cost $1.7 billion to $1.8 billion, according to Mitchell of Trans-Elect. The second phase to complete the 350-mile line could be finished by 2020, he said.

The mid-Atlantic region is well-suited for the project because its strong winds and shallow waters allow easier installation of turbines as far as 15 miles offshore, making them invisible from land, Google said.

The transmission network will be able to connect to 6,000 megawatts of power from wind turbines, Google said. That’s equivalent to 60 percent of the wind energy installed in the U.S. last year, the company said.

Globally, wind power is expected to account for 22 percent of the world’s electricity generation within two decades.