NEW YORK — With the price of gas above $3.50 a gallon in all but one state, there are signs that Americans are cutting back on driving, reversing a steady increase in demand for fuel as the economy improves.

Gas sales have fallen for five straight weeks, the first time that has happened since November, according to MasterCard SpendingPulse, which tracks spending at 140,000 service stations nationwide.

Before the decline, demand was increasing for two months. Some analysts had expected the trend to continue because the economic recovery is picking up, adding 216,000 jobs in March.

“More people are going to work,” said John Gamel, director of gasoline research for MasterCard. “That means more people are driving and they should be buying more gas.”

Instead, about 70 percent of the nation’s major gas-station chains say sales have fallen, according to a March survey by the Oil Price Information Service. More than half reported a drop of 3 percent or more — the sharpest since the summer of 2008, when gas soared past $4 a gallon.

This year, gas prices have shot up as unrest in North Africa and the Middle East rattled energy markets and increased global demand for crude oil squeezed supplies. A gallon of unleaded regular costs $3.77 on average, and only Wyoming has an average lower than $3.50. Gas is already 41 cents more expensive then at this point in 2008, when it peaked at $4.11 in July.

Most analysts are sticking to forecasts of a high of $4 a gallon, though some have predicted $5 gas.

Across the country, some drivers are already hunting for cheaper gas, sometimes with the help of a mobile phone app.

Kim Cramer, who works for Radio Flyer in Chicago, has started walking and carpooling more. She’s also learned to be choosy, buying gas in suburbs, where she’s learned she can save as much as 20 cents a gallon.

“I try to fill up anywhere besides the city,” she said.