Crude oil prices plunged again on Thursday, reaching a record 12-year low as concerns of a global slowdown led by China sparked more declines. But how low can gas price go at the pump?

The global oil glut contributed to the precipitous decline over the past 18 months that has wiped out prices by a massive 70% as they dipped to $33 a barrel on Thursday, levels last seen in 2004. As drivers in Houston saw gasoline prices tumble to $1.50 per gallon, the potential of gasoline prices weakening to a mere $1 per gallon became more of a likelihood.

How Gasoline Can Tumble Below $1.50

“It’s not improbable that retail gasoline prices could tumble close to $1 per gallon this winter in some parts of the U.S.,” said Bernard Weinstein, a business economist at Southern Methodist University’s Cox School of Business in Dallas.

Gasoline prices will “get crushed soon,” which bodes well for drivers, but how far it will decline remains a question, said Chris Faulkner, CEO of Breitling Energy, a Dallas oil and gas exploration and production company.

One major component of gas prices consists of transportation costs and in markets such as Houston where those expenditures are reduced, prices could “easily break $1.50, but it probably won’t hold long, so drivers in those markets should fill ‘er up and smile while they can,” he said. “Other coastal regions near refineries could enjoy the same discounts.”

Prices at gas pumps across the country are averaging $1.98 a gallon in many states, according to Gasbuddy.com, a Gaithersburg, Md.-based provider of retail fuel pricing information and data.. The lowest price is in Missouri where gas is $1.68 a gallon, and the highest price is at $2.88 a gallon n California.

The potential for gasoline prices to keep plummeting “grow daily,” said Bruce Bullock, director of the Maguire Energy Institute in Dallas.

“Though unlikely, $1 a gallon gasoline in certain parts of the country is certainly not out of the realm of possibility,” he said. “The last time the U.S. enjoyed gasoline prices below $1 was in the late 1990s.”

Why $1 Looks Unlikely

An even sharper decline to $1 a gallon is not probable, because aside from the cost of crude oil, three other components determine the price of oil, including taxes, the margin for refining and the margin for the retail and distribution segment of the market, said Timothy Hess, a lead analyst for the Energy Information Administration, the independent statistical arm of the Department of Energy based in Washington, D.C. During the past four years, the other three fees averaged $0.67 cents per gallon along the Gulf Coast during the first quarter of the year with the lowest being the first quarter of 2014 at $0.60 per gallon.

In order for retail gasoline to dip to $1 per gallon that means crude oil would have to sell for $0.33 per gallon at $14 a barrel in the average year, or $0.40 per gallon or $17 per barrel when refining and retail margins are low, Hess said. The EIA estimates that gasoline will average $2.36 per gallon in 2016.

“Right now margins are above where they’ve been the past few years,” he said. “EIA doesn’t forecast crude prices getting to that level.

While $1 per gallon gasoline may not be realistic, having the price dip even further to $1.25 “is certainly within reach,” said Patrick Morris, CEO of New York-based HAGIN Investment Management.

Since the taxes imposed by each state vary and in states such as New York and California where they are higher, it may not be plausible. Other states with lower taxes for gasoline “should see very low prices,” Morris said.

“Of course, it is unsustainable because low fuel costs drive consumption,” he added.

The national average tax rate for gasoline is higher at 50 cents per gallon compared to 38.4 cents in Texas, and crude oil prices would have to continue to decline for gas to drop to $1, said Ryan Mossman, a senior director for Insite360 FuelQuest, a Houston-based provider of fuel procurement and logistics software for fuel buyers.

“You would have to see quite a bit more of a fall in crude oil costs, retail margins, logistics costs and refining costs to approach $1 gasoline,” he said.

Even if drivers find gasoline for $1 a gallon, it is because a gas station is merely seeking publicity and will not profit from that decision, said Will Speer, a senior petroleum analyst at GasBuddy.com.

“A 50 cent drop in two months is very unlikely, even though gas in Houston is $1.50,” he said.

Gasoline prices will trend upwards naturally in the next two months as producers transition to a summer grade gasoline and as refiners conduct their routine maintenance, which will lessen the supply, Speer said. Even if prices remain under $2.00 a gallon in January, the uptick will occur by March.

“With less supply and the summer blend around the corner, prices will start to rise,” he said.

Production Levels Have Not Dropped

Despite the immense oil surplus, producers globally and even in the U.S. have not slowed down.

The glut is not dissipating in the near term, since U.S. producers are still producing crude at the same rate as last year and inventory rose by 26% in 2015 despite increased demand, Speer said. While prices will remain around the $2 range in January, the national average will rise to $2.70 range in May.

Not only do global supply and demand affect the prices of oil and gasoline, but political agendas also play a large factor as some of the world’s largest producers are jockeying for the top position. Saudi Arabia is currently pumping more than 10 million barrels a day in an “attempt to undermine the economies of Iran and its ally Russia,” said Weinstein. “Meanwhile, production has been slow to decline in America’s shale plays as lifting costs have fallen in tandem with prices. In addition, domestic inventories of gasoline are at record levels.”

While prices bottomed out during the financial crisis, the recession from 2000 to 2001 and the Asian crisis from 1996 to 1998, current prices are “near the bottom of the current commodity cycle, so I don’t expect retail gasoline prices to reach $1 per gallon,” said Rob Thummel, a portfolio manager with Tortoise Capital in Leawood, Kan. which has $13.5 billion under management invested in energy stocks.

“Oil prices would have to approach $10 per barrel for gasoline prices to reach $1 per gallon and I don’t expect oil prices to fall this low,” he said.

Gasoline prices are historically low as viewed by the 50-year inflation adjusted price of gasoline which is $2.50 per gallon, said Faulkner.

“These are unprecedented times and we have been enjoying prices that are well below the long-term average for an extended time now,” he said. “Remember, gas prices rocket up and float down like a feather. Think about telling your grandkids when you remember $1.50 gasoline. It’s unheard of in our generation, really.”