HOUSTON—The U.S. petrochemical industry, in trouble just a few years ago, is making a spectacular comeback thanks to the boom in shale gas, shaking up the industry worldwide and spreading some discomfort through Asia and Europe.

"It's pretty simple: There's just so much feedstock that needs to find a home," said Chuck Carr, a petrochemical analyst at IHS, in Texas, the capital of the U.S. industry. "So everybody's saying, 'Hurry up to build something,' because at that natural gas price, it's just pure value."

The surge in gas production has pushed gas prices in the United States down since 2009, while oil prices have doubled since then.

The low price for gas as a fuel is already helping a comeback in U.S. industry. Natural gas sells for one third the price in Europe and one fifth that in Asia.

But that makes it even more a boon for the petrochemical industry, where gas is a core raw material for producing plastics and other basic industrial products.

In 2008, none of the members of the American Chemistry Council foresaw investing any more in the country.

Now, in the wake of the shale gas boom, the ACC lists 110 new investment projects for the U.S., worth some $77 billion.

Just in the past two months, 13 projects have been announced.

If all of those projects come to fruition, the ACC sees 46,000 new direct jobs, plus another 200,000 for subcontractors, in a sector that employs 800,000, compared with 1.1 million in 1981.

"I've been working for the chemical industry for almost 20 years now, and it's always been a story of moderating production," said Martha Moore, an ACC economist. "Now we're in a renaissance. Chemicals are at the forefront, but there's a rebirth of manufacturing in the United States. It's a very exciting time to be in the industry."