Cyber Monday this year once again set a record as the biggest online sales day ever in the U.S. If current online shopping trends continue, though, the record will only last for a year.

Online sales came in higher than expected on the Monday following the Black Friday weekend to reach $3.45 billion, a 12.1 percent increase over last year, according to Adobe Digital Insights. In Minnesota, online sales jumped 17 percent to $250 million over the five days of spending that spanned Thanksgiving to Cyber Monday.

That blockbuster performance was despite many retailers starting their Cyber Monday sales early. Minneapolis-based Target Corp. not only started its 15 percent off sale a day early but also extended the promotion to its stores. And Wal-Mart launched its Cyber Monday deals on Black Friday.

Meanwhile, many retailers are running online deals all week in what they are calling Cyber Week. Amazon.com said it would offer more than 75,000 deals this week, adding new promotions every five minutes.

The vast majority of spending still happens in stores. But as online shopping continues to rise in popularity, it is putting a damper on mall traffic.

A survey for the National Retail Federation found that more people shopped online than in stores over the Black Friday weekend as some shoppers looked to avoid the crowds and hassle.

Over Thanksgiving Day and Black Friday, the firm ShopperTrak said in-store traffic dropped 1 percent, a result of fewer stores being open on Thanksgiving and more people shopping online.

Still, Mike Baker, an analyst with Deutsche Bank, noted that was the best in-store performance since 2011.

"We believe the holiday season is off to a good start," he wrote in a research note.

Last week, Target and Kohl's said they had their biggest online sales day ever on Thanksgiving Day. But Target officials were mum on Tuesday about whether this year's Cyber Monday set another company record. Last year, its Cyber Monday promotion was so popular that Target.com couldn't handle all of the traffic. This year, its website didn't have any major hiccups as the company spread the promotion to stores and has also been working to upgrade its systems.

"The two-day 15 percent off sitewide, storewide promotion was a first-of-its-kind for Target," Mike McNamara, Target's chief information officer, said in a statement. "Our guests were excited about the offer and we were pleased with the Target.com site performance, which provided guests with a great online shopping experience throughout the duration of the promotion."

Adobe has forecast online sales to grow 11 percent this holiday shopping season. Sales are already up 7.6 percent since Nov. 1.

Data also shows that consumers are increasingly using their smartphones to shop. On Cyber Monday, mobile sales from tablets and smartphones accounted for 47 percent of online traffic and 31 percent of online sales, Adobe said. Some of the top-selling items of the day included Sony PlayStation 4, Microsoft Xbox, Samsung 4K TVs, Apple iPhone, Lego sets, Amazon Fire, Nerf, Shopkins, Barbie and Pie Face Game.

Tamara Gaffney, principal analyst for Adobe, noted that online sales on Black Friday, which grew 22 percent to reach $3.34 billion this year, are now nearly as big as on Cyber Monday.

"We'll be watching this closely next year as Black Friday could be the one to top the records," she said in a statement.

Adobe compiles its data by measuring 80 percent of all online transactions from the top 100 U.S. retailers.