U.S. retail sales rose 4 percent in the 2010 holiday selling season and should rise 2.2 percent in the first quarter of this year, a group that measures customer traffic in retail locations said on Monday.

Despite the overall sales rise, shopper traffic in November and December -- the biggest selling season of the year for U.S. retailers -- was flat as budget-conscious shoppers made fewer trips to malls but spent more on each visit, ShopperTrak said.

ShopperTrak expects shopper traffic to rise 2.8 percent in the first quarter.

Although we're still essentially comparing to depressed levels, the 4 percent sales rise this season is the first real positivity in two years and should be seen as a relatively encouraging sign for retailers heading into 2011, Bill Martin, co-founder of ShopperTrak, said at the National Retail Federation conference in New York.

Moody's Analytics chief economist Mark Zandi also forecast sales gains in 2011 and 2012 for retailers.

Going into 2011, there are reasons to be upbeat: The job market is clearly improving, the stock market, credit is starting to flow a little more freely, Zandi said at the NRF convention.

Echoing the sentiments of chief executives, including J.C. Penney's Myron Ullman, Zandi praised U.S. government initiatives such as lower payroll taxes that kicked in this month and said the Federal Reserve and tax authorities have to be aggressive to boost consumer spending. Consumer spending accounts for about 70 percent of the U.S. economy.

We need to make sure that the economic recovery evolves into a self-sustaining economic expansion, Zandi said. He expects the rate of U.S. job creation of about 100,000 per month in recent months to pick up steam, starting this spring.

The International Council of Shopping Centers has forecast an increase of between 3 percent and 3.5 percent in same-store sales at leading U.S. chains in 2011.

The Standard & Poor's Retail Index <.RLX> was up 0.21 percent in afternoon trading on Monday, compared with a 0.18 percent decline in the broader S&P 500's <.SPX>.

(Editing by Gunna Dickson and Steve Orlofsky)