NEW YORK (CNN/Money) - Early sales reports point to healthy growth this holiday shopping season.

On Sunday, Visa USA reported that spending on its credit and debit cards for the two days following Thanksgiving rose 12 percent to $6.5 billion.

On Saturday, Wal-Mart Stores -- the nation's largest retailer -- said that sales at its U.S. stores grew 6.3 percent to a record $1.52 billion on the day after Thanksgiving, up from $1.43 billion on the same day a year earlier.

ShopperTrak, which measures retail sales, said retail stores took in $7.2 billion in sales on Friday, up 4.8 percent from a year earlier.

Such reports could indicate that the big retail weekend was living up to expectations for improvement over last year, when the holiday season generated the smallest sales gain in more than 30 years.

Black Friday" gets its name from the hope that on that day merchants' financial statements will move out of the red and into the black. The traditional start to the holiday shopping season generates as much as 40 percent of annual revenues and nearly all the year's profits for key gift destinations such as toy stores and apparel chains.

Black Friday was once the biggest shopping day of the year, but in recent years that title has gone to the Saturday before Christmas. This year is likely to be no exception.

The National Retail Federation (NRF), the industry's largest trade group, expects industry sales for the key November and December shopping period to grow 5.7 percent, the largest rise since 1999, to $217.4 billion.

But despite the NRF's bullish outlook, some industry watchers are cautious.

The consensus among analysts is that holiday spending this year will be solid, if not spectacular, averaging a smaller 4 percent growth.

"The consumer is jittery," said Richard Hastings, chief retail analyst with Bernard Sands. "Rising debt levels, inflation and higher gasoline prices are all real threats and a drag on spending."

Despite signs of a pickup in the economy and an improving labor market, consumers don't appear to be feeling the Yuletide cheer.

"The economy still has to prove itself and create millions of new jobs," Hastings said.

The Conference Board in a survey last week said U.S. households on average are expected to spend $455 on gifts this year, down 5 percent from 2002.