FORGET the turkey and the football - if it's Thanksgiving, why aren't you shopping?

United States retailers trying to squeeze every extra cent out of shoppers opened for Thanksgiving yesterday, trying to get a jump on the holiday shopping season.

Among the retailers that opened were Wal-Mart Stores Inc's US discount stores, 850 of Gap Inc's Old Navy stores, some of its Gap and Banana Republic stores; and Sears Holdings Corp's namesake department stores, and Kmart discount stores.

For retailers, opening the stores amount to extra sales at the start of what is expected to be the best holiday shopping season since 2007-- before falling home prices, tight credit and soaring unemployment forced consumers to cut spending. The holiday season is essential for many retailers, who depend on it for a big part of their profits for the year.

But people shopping yesterday will still only be a fraction of the 138 million the National Retail Federation hopes to see on today known as Black Friday.

"It's an add-on," Brian Sozzi, an analyst at Wall Street Strategies, said, of stores opening on Thanksgiving Thursday.