Despite saying they are outraged by it, data shows more shoppers shifting buying to Thanksgiving Day

NEW YORK (CNNMoney) -- Shoppers increasingly are shifting their buying to Thanksgiving Day, despite petitions against stores opening on the holiday -- and the powerful lure of the post-turkey nap.

According to early estimates on Black Friday from Shoppertrak, sales at brick-and-mortar stores were down slightly to $12.29 billion in 2014 vs. $12.35 billion a year earlier. But spending was up nearly 24% on Thanksgiving, and slipped 6.9% on Black Friday, Shoppertrak found.

What's more, people were more willing to trek to stores on Thanksgiving: Visits were up 27% on Thursday compared to 2013, but they were down 5.6% on Black Friday, according to Shoppertrak.

Still, shoppers spent nearly three times as much -- $9.1 billion -- on Black Friday than on Thursday, Shoppertrak estimates.

The trend was similar online, with shoppers increasingly willing to buy on Thanksgiving. Online sales were up 14.3% on Turkey Day compared to last year, according to IBM's Digital Analytics Benchmark report, but just 9.5% on Black Friday, less than expected.

Shoppers also are using their phones and tablets more than ever -- both to buy and comparison-shop while in stores, IBM found.

Sales on mobile devices were up more than 28% from Black Friday last year, accounting for more than one in four online sales transactions Friday, IBM found.

IBM had projected online shopping would climb 15% for the period from Thanksgiving through Monday. It projected year-over-year growth of 13% on Black Friday.

Wal-Mart, the world's largest retailer, said it shattered sales records on Thanksgiving, posting its second-biggest online sales day. The company said its site saw over 500 million page views, and 70% came from mobile traffic.

Overall, the National Retail Federation projected spending this season will climb 4.1% to $616.9 billion. It estimated online sales would grow between 8% and 11%.

Last year, holiday sales climbed 3.1%, according to the NRF.

The preliminary reports from Shoppertrak and IBM give an early peek at some of the busiest shopping days of the year.

Black Friday isn't the one-day event that it used to be, when malls and department stores threw open their doors at midnight.

Nowadays, there's round after round of "door busters" and a slew of online sales that begin days before Friday. And most major retailers advertise "Black Friday" deals that actually begin Thanksgiving Thursday evening.