HOUSTON – Dow Chemical Co. spent a decade moving chemical production to the Middle East and Asia. Now it’s leading the biggest expansion ever seen back home in the United States as shale gas revives the industry’s economics.

Dow is among companies planning to build crackers, industrial plants typically costing $1.5 billion apiece that process hydrocarbons into ethylene and other synthetic materials.

The new crackers will be the first to be built in the United States since 2001 and the largest wave of additional capacity, John Stekla, a director at Chemical Market Associates Inc., a Houston-based consultant, said.

Driving this renaissance is the plunge in the price of natural gas, used in crackers as a raw material, to a nine-year low.

New drilling methods are opening up vast shale formations from Texas to West Virginia. U.S. chemical investments stemming from shale gas may top $16 billion, creating 17,000 jobs directly and another 400,000 indirectly, according to the American Chemistry Council, a Washington-based industry group.

“The U.S. now has investment-grade economics, and because of shale we are going to lock those economics in,” Dow Chief Executive Officer Andrew Liveris said. “We can grow our Americas base off our U.S. Gulf Coast assets. That is a big change.”

Dow will spend about $4 billion to construct a cracker near the Gulf Coast by 2017, reopen another in Louisiana, and build two propylene plants, Liveris said in a telephone interview from Dow’s Midland, Mich., headquarters.

That investment will supply ingredients for Dow plants making high-margin products such as paint additives and automotive plastics.

Occidental Chemical, Chevron Phillips Chemical and Formosa Plastics have said in the past nine months they too may build crackers on the Gulf Coast, while LyondellBasell Industries may invest in one. Royal Dutch Shell said in June it plans to build a cracker in Appalachia, the region’s first in half a century.

Six shuttered crackers also are reopening, and more are being expanded.

The flurry of announcements contrasts with the woes previously inflicted by volatile energy prices on the industry.

U.S. chemical-industry employment fell to 782,000 from a peak of 1.1 million in 1981, Kevin Swift, chief economist for the American Chemistry Council, said in an interview.

Dow, the world’s biggest maker of ethylene and polyethylene, employs 25,000 people in the U.S. The company will add 500 manufacturing and 2,500 construction jobs with its Gulf Coast expansion, said Liveris, whom President Barack Obama appointed in June to co-chair the Advanced Manufacturing Partnership, which is tasked with improving U.S. manufacturing competitiveness.

Increased U.S. gas production has helped create a cost advantage over producers in Europe and Asia, where petrochemicals are made primarily from oil derivatives. Shale gas may account for 47 percent of total U.S. gas production in 2035, up from 16 percent in 2009, according to the Energy Information Administration.

“Everyone called the U.S. commodity chemical industry dead a few years ago,” Mark Demos, who helps manage $18 billion as a fund manager at Fifth Third Asset Management in Minneapolis, said in an interview. “All the sudden, with plentiful natural gas, the margin story in commodity chemicals looks pretty favorable.”

Still, environmental concerns may lead the government to restrict shale-gas drilling, which in turn could drive gas prices higher. Restrictions on exploration in New York and parts of Pennsylvania have increased chemical producers’ anxieties about their new plants, Peter Oosterveer, president of energy and chemicals at Fluor Corp., which builds crackers, said.

Food & Water Watch and the Natural Resources Defense Council are among environmental groups seeking full or partial bans on hydraulic fracturing, or fracking, which releases gas from shale-rock formations.

The process, in which millions of gallons of chemically treated water are forced underground to free the gas, can contaminate drinking water, the groups say. The American Chemistry Council, which is funded by chemical producers, supports state-level oversight of fracking to address the public’s concerns.