Which retailers get hurt the most by rising gas prices? Wal-Mart (WMT), J.C. Penney, Kohl's (KSS) and Kroger (KR), according to one analyst.

And which retailers aren't as vulnerable to changes at the pump? Costco (COST), Macy's (M) and BJ's Wholesale Club (BJ).

The reason is because poorer families in America are hurt more by gas price hikes and high unemployment levels, Bloomberg reports. And poorer families prefer to shop at Wal-Mart, one analyst says.

The analyst, Richard Hastings of Global Hunter Securities, studied the income levels of shoppers and found that 82% of Wal-Mart shoppers make less than $75,000 a year. That compares with 63% of BJ's shoppers and 55% of Costco members that make less than $75,000 a year.

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About 8% of Wal-Mart shoppers earn more than $100,000 a year, compared with 28% at Costco and 25% at BJ's.

Higher gas prices will put the squeeze on some families. And for some, that will directly translate into fewer clothing purchases. That could be a problem at Kohl's, where 29% of shoppers said that if gas prices go up, their clothes budget goes down, Bloomberg reports.

"If you’re living paycheck to paycheck or you’re on a fixed income, the rise of gas prices impacts your habits," a AAA spokesman told Bloomberg. "If you’re more affluent and can afford gasoline at any price, then you’re going to drive regardless."

Today's average gas price is $3.56 for regular gas, according to AAA's Fuel Gauge Report. A month ago, the average price for regular was $3.13, and a year ago the average price was $2.79.

Gas prices aren't the only thing on the rise. Economists think the prices of all goods and services will rise 2.3% this year, Bloomberg reports. But wages aren't matching that increase. Average hourly earnings only rose at a 1.9% annual rate in January.