By MAE ANDERSONNEW YORK (AP) â¿¿ So much for new spring shorts and T-shirts. As cold weather lingered across most of the country, Americans shopped modestly in March. U.S. retailers reported a key revenue figure rose slightly during the month, as shoppers held back on spending because of the cold weather across the nation, particularly the Midwest and East Coast, and continued fears about the economy. Economists monitor consumer spending because it accounts for more than 70 percent of economic activity. According to a preliminary tally of 15 retailers by the International Council of Shopping Centers, revenue in stores open at least a year rose 1.4 percent, or 2.2 percent excluding drugstores. That was below expectations, said Michael Niemira, chief economist at the ICSC. Revenue in stores open at least one year is a key measure of a retailer's financial health, because it excludes stores that open or close during the year. Weather was a factor, with March being the coldest in seven years. The comparison with last March was especially tough. Last year saw the warmest March on record, according to weather research firm Planalytics Inc. "Wintry weather conditions persisted deep into March, depressing spring apparel, home and garden, and seasonal merchandise sales," said Ken Perkins, president of Retail Metrics. Meanwhile, the payroll tax increase that took effect in January and the uncertain economy have weighed on spending, he said. Analysts often like to combine March and April to get a clearer picture of shoppers' habits, because of volatile weather patterns that time of year and Easter's movement around the calendar. Easter tends to help stores that sell groceries and candy but costs clothing sellers a day of sales without spurring much additional spending. Most of the stores that report monthly sales figures are clothing specialists. Job fears have risen since the government reported hiring was the slowest in nine months in March. However, the Labor Department reported Thursday that the number of Americans seeking unemployment benefits fell sharply last week, a hopeful sign that the slowdown in hiring may have been temporary.