Average U.S. gas prices are expected to drop below $3 per gallon by Saturday, a psychologically significant milestone that comes after a months-long fall in the price of crude oil.

The free fall amounts to a stimulus for consumers, yielding tens of billions in savings just before the holiday season. U.S. gas prices, which hovered around $3.60 per gallon in June, haven’t been below the $3 mark since late 2010, according to AAA, which tracks fluctuations.

“Most Americans had sort of come to the point where they were frustrated that they were paying higher prices than they wanted,” said Michael Green, an AAA spokesman. “They’d become sort of resigned to paying $3 and higher into the future.”

Plummeting gas prices could ultimately cause complicated economic ripples, prompting domestic energy companies to rethink the scale of energy production.

But for now, economists say, American consumers are seeing the first clear fruits of this country’s oil and gas boom. The shale revolution has helped the United States become the world’s biggest oil producer, which has driven down the price of crude and allowed for less dependence on imports.

If gas prices had stayed as they were in June, consumers would have spent $381 billion at the pump for the year, according to IHS, a leading adviser on energy. If gas prices stay as they are now, consumers will spend $341 billion at the pump.

That $40 billion difference amounts to about 0.2 percent of the U.S. gross domestic product, and the “vast majority” of this savings is being “redeployed as spending on other items,” IHS said. The lower class benefits the most; the poorest fifth of Americans spend somewhere between 8 to 13 percent of their after-taxes income on gasoline.

In part, gas prices change seasonally. U.S. regulations require a cleaner-burning and more expensive gas in the summer months. Oil prices also tend to fall when the global economy sags – in this case, with a slowdown in emerging markets and a potential looming recession in Europe.

But those are hardly the largest factors: The world is also flush with oil. Fracking technology has allowed for a booming supply in the United States and Canada, while both Iraq and Libya have both recently upped their flows. Some analysts now see the making of a price war.