In 1925, the average price of gas was 10 cents a gallon.
The price of a gallon of gas in 1990 varied from $1.10 to $1.30
In 1925, gasoline cost 20 to 23 cents a gallon as evidenced by this photo: http://www.shorpy.com/node/3835?size=_original. Adjusted for inflation to 2009 dollars, that was $2.43 to $2.79 a gallon. As of 3/23/2009, the average price of gasoline on the East Coast, where this photo was taken, was $1.94 per gallon.
the average price per gallon of gas in 1988 was $1.08
The price per gallon of gasoline in 1914 was about $.17/gallon.
In 1979, the average cost for a gallon of gas was $0.86.
In 2005, the average price per gallon of regular unleaded gas was $2.30
the average gas price for a gallon was $1.85 in the year of 1994.
In 1997, the average price per gallon of regular unleaded gas was $1.23
About .20/Gallon
In 1925, the average cost of a gallon of gas in the United States was about 18 to 25 cents. This price reflected the economic conditions of the time, including the growth of the automotive industry and changes in oil production. Adjusted for inflation, this cost would be significantly lower than today's prices.
As of June 9, 2010, the average price of a gallon of regular gas in Missouri is $2.518