NEW YORK (TheStreet) -- The last time gasoline prices were this low, President George W. Bush was ramping up for the invasion of Iraq and a little-known Barack Obama was finishing his second term as an Illinois state senator.

Except for a brief but dramatic plunge after the 2008 the financial crisis, gasoline prices haven't been this cheap in a decade. With crude oil prices falling below $50, gas is likely to get even cheaper.

There's no telling how long it goes on for," said Robert Sinclair, Jr. the American Automobile Association's manager of media relations in New York.

The current U.S. average price is now $2.19 for a gallon of regular fuel. That makes it cheaper than a gallon of milk, which averages about $3.70 a gallon. In 2004, when gas was about $2, milk cost about $3 a gallon.

The record high for gasoline came in July 2008 -- just before the financial crisis -- when it averaged $4.43 a gallon. The lowest in recent memory came in January 2009 during the financial crisis, when the cost of a gallon of regular briefly fell below $2.

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For older Americans, the current rate for fuel pales compared to the 1970s and 1990s. Aside from a spike in oil prices coinciding with the Sept. 11, 2001, attacks, the only other time period when gas maintained a prolonged price north of $2.50 per gallon was the early- to mid-1980s, when the U.S. faced a volatile fuel market and strained relations in the Middle East.

Still, the drop in gas prices is expected to save Americans $92 billion a year. For the average 15-gallon tank of gas, the typical consumer is spending $20 less at the pump than he or she did in April 2014, potentially providing the U.S. economy with a short-term shot in the arm.

Some car rental companies are increasing rates, Sinclair said, a sign that rentals are back in demand. And automakers are seeing rising sales of SUVs and pickup trucks as Americans apparently believe low gas prices are here to stay.