Unbelievably, in some quarters there is still debate over the extent of the impact of the shale revolution on the U.S. economy. The evidence can be murky, but common sense says the impact is quite large.

“The oil and gas industry is about 1% of the U.S. economy today, and that is something that stops my oil and gas colleagues,” said Stephen Gallagher, managing director and head of research for Societe Generale in the Americas.

“By region, by company, by sector, the numbers can be quite large, in the billions of dollars, but in aggregate it’s a small percentage of U.S. GDP,” he said, speaking at the Houston Energy Finance Group recently.

“But the U.S. economy would be in a lot worse shape if not for higher oil and gas prices encouraging new supplies to come online,” he said. “While we are looking at tens of billions of dollars from drilling, production, new pipelines and so on, some of this economic impact is substitution for losses elsewhere in the economy, and not a net gain—like replacing the coal producers …,” he said.

Oil and gas production growth adds about 0.1% to gross domestic product (GDP) growth, while added consumer purchasing power thanks to low gasoline and low electricity prices, adds 0.1 to 0.2% to GDP. Infrastructure gains and “onshoring” of manufacturing, and more U.S. exports, each adds another 0.1%.

Still, 0.1% of GDP is $15 billion to $20 billion of GDP gains per year in the U.S. economy, and $330 billion over 10 years, if the oil and gas industry were to add 0.2%.

Gallagher likened it to the effects of the Internet and the percent of GDP that it added to the economy 20 years ago. At first the Internet added only a few percentage points per year to GDP, but today, the cumulative effect is big.

“I think oil and gas will have a similar effect, but not as large as the Internet has,adding maybe three-tenths of a percent to GDP because it is not so much that it is adding something new, as it is a substitution [for declines in other industries].”