With e-commerce on the rise, brick-and-mortar retailers continue to push their online sites as the holiday shopping season approaches. Target Corp. announced a week of online-only deals around Cyber Monday that promise extra-deep discounts on toys, kitchen appliances and items for the home. The Minneapolis-based retailer will start its seven-day blitz the Sunday after Thanksgiving.

Target and nearly all major retail chains have invested in improving their digital shopping experience as consumers increasingly use their mobile phones and laptops to buy items that they'll either pick up in stores or have them shipped to their homes.

Research released Monday by research marketing firm NPD Group found that consumers last year spent 20 percent more through online and mobile shopping than at brick-and-mortar stores during the flurry of promotions around Thanksgiving and Cyber Monday.

Analysis from NPD Group's receipt mining service, Checkout, found that shoppers spent $108 in stores on the Friday after Thanksgiving, compared to $134 that same day in digital orders.

Cyber Monday, a promotional event for the Monday after Thanksgiving created by retailers to generate online sales, was the second busiest shopping day behind Black Friday's e-commerce sales, according to Checkout. Consumers spent an average $131 each.

"Online shopping drives significant holiday spending over those peak days, particularly among the early birds," Marshal Cohen, NPD's chief retail industry advisor, said in a statement. "Some traditions remain, but more and more consumers are forgoing the Black Friday trip to the mall and doing their shopping online over more days."

NPD's research parsed shopping habits and found that shoppers are more likely to buy some things online and others they prefer the in-store experience. Last year, Black Friday was the most important day for in-store apparel spending per buyer, while Thanksgiving was the dominant day for housewares and technology products, which could signal a busy day for Richfield-based Best Buy, which opens stores at 5 p.m. on Thanksgiving this year.