CHICAGO — Retailers saw increased foot traffic this Black Friday, but that didn't generate higher sales, according to ShopperTrak, the world's largest counter of retail foot traffic.

According to ShopperTrak's analysis, when compared to Black Friday 2011, retail foot traffic rose 3.5%, to more than 307.67 million store visits. However, retail sales decreased 1.8%, with shoppers spending an estimated $11.2 billion on Friday, compared to $11.4 billion last year.

While sales may have slipped on Friday, those figures do not encapsulate the entire weekend. "Black Friday continues to be an important day in retail," said Bill Martin, ShopperTrak founder. "This year, though, more retailers than last year began their 'doorbuster' deals on Thursday, Thanksgiving itself. So while foot traffic did increase on Friday, those Thursday deals attracted some of the spending that is usually meant for Friday."

For more, you can access graphics from ShopperTrak's analysis at this link. On Tuesday, ShopperTrak will unveil their estimates for the entire 'Black' Weekend, which will provide a better understanding of the overall picture for retailers this holiday season.