New York ? Americans didn’t stop splurging after the holidays.

They braved snowstorms and shopped in force in January, handing retailers like Costco, Victoria’s Secret and Macy’s surprisingly strong sales.

Along with two encouraging economic reports — the biggest service sector expansion in five years and a plunge in weekly unemployment claims — the sales figures offered more evidence Thursday that the economic recovery is picking up speed.

“It’s one more piece of the economic puzzle that’s falling in place,” said Michael P. Niemira, chief economist at the International Council of Shopping Centers.

Consumer spending has been improving for more than a year now, and this holiday season was the strongest for stores since 2006, before the Great Recession, according to the council. Sales figures for January showed that shoppers weren’t spent out after Christmas.

The council’s index of 32 stores showed a robust 4.8 percent increase for the month, well above the expected 1.5 to 2 percent. Analysts were worried that snowstorm after snowstorm, particularly in the Northeast, might have kept shoppers at home.

The figures cover Jan. 2 through Saturday for stores that have been open at least a year.

Consumer spending accounts for about 70 percent of U.S. economic activity, so how shoppers behave is an important measure of economic health.