Gasoline prices in the United States have reached their highest levels in more than two years.

According to American Automobile Association , the national average for a gallon of regular unleaded gasoline is $3.10, which is 37 cents higher than it was at this time last year.

Average pump prices in major cities range from $2.91 in Denver to $3.38 in San Francisco. Drivers in New York City pay about $3.19 a gallon, while gas stations charge $3.24 a gallon in Chicago and $3.37 in Los Angeles. In Boston, gas goes for $3.11 a gallon. It's $2.92 in Houston and $3.20 a gallon in Miami.

Analysts say the higher gas prices have caused Americans to cut back in other areas in their lives, including eating and entertainment venues.

Diane Swonk, chief economist at Mesirow Financial, estimates gasoline prices are affecting the spending habits of more than half of U.S. drivers

The International Energy Agency predicted that worldwide economic growth and a cold winter in the northern hemisphere will support higher-than-expected oil demand this year.

Some analysts have predicted gas prices in some major cities will top $4.00 a gallon by this spring.