But many stores evidently felt they needed an edge, especially this season, when many Americans are worried about high unemployment and wondering whether Congress will be able to head off tax increases and spending cuts before the U.S. reaches the "fiscal cliff" in January.Overall, the National Retail Federation estimates that sales in November and December will rise 4.1 percent this year to $586.1 billion, below last year's 5.6 percent. "Every retailer wants to beat everyone else," said C. Britt Beemer, chairman of America's Research Group, a firm based in Charleston, S.C. "Shoppers love it." At Wal-Mart, the world's largest retailer, most of its 4,000 U.S. namesake stores are already open 24 hours year-round. But the chain added special sales at 8 p.m. on Thanksgiving, two hours earlier than a year ago. The company said that its start to the holiday season was "the best ever," with nearly 10 million transactions and 5,000 items sold per second from 8 p.m. to midnight on Thanksgiving. Toys R Us opened at 8 p.m. on Thanksgiving, an hour earlier than last year. Macy's, which opened at midnight on Thanksgiving, had 12,000 customers wrapped around its store in New York's Herald Square. The earlier start also meant the violence associated with shoppers fighting for bargains likewise began earlier. On Thanksgiving night, a couple was struck by an SUV while walking into a Wal-Mart in Washington state, and in Texas, shoppers scattered when a man who got punched during a fight at a Sears store pulled a gun. Two people also were shot and wounded in Tallahassee, Fla., on Friday in a disagreement that police believe was over a parking spot outside a Wal-Mart. Julie Hansen, a spokeswoman at Minneapolis' Mall of America, the nation's largest shopping center, reported that 30,000 shoppers showed up for the mall's midnight opening, up from 20,000 last year. "This was additional dollars," Hansen said. This year, 200 of the 520 mall tenants opened at midnight following Thanksgiving. That's double from a year ago.