For the average retailer, Cyber Monday is the biggest online sales day of the year, with revenues three times greater than a normal day. Earlier this week, nearly $2 billion was spent online on Cyber Monday, a new record, according to an analysis by the Adobe Digital Index. But as it turns out, Cyber Monday is not the biggest online sales day for everybody. In fact, big-box brick-and-mortar stores tend to experience higher online sales on Black Friday than on Cyber Monday. So why do these merchants perform better online on the day when everybody is crammed into the store at 5 AM than on the day when people are supposed to be at home shopping from the comfort of their own computer? The answer is simple: showrooming.

Showrooming is that oh-so-common phenomenon when customers visit a brick-and-mortar store to scope out merchandise in person only to make their purchase online, sometimes from a different retailer. Fueled by the growth of high-speed mobile internet connections, showrooming is becoming increasingly popular. And while this has been cause for concern for many traditional retailers, some retailers have embraced the trend with open arms, adding QR codes to the labels of popular products, developing mobile apps optimized for in-store shopping, and ensuring that the transition from physical shopping to virtual shopping is as seamless as possible.

The rise of showrooming during the holiday season raises an interesting question: Is it possible that showrooming may one day become more popular than Cyber Monday? Let’s look at the data.

This year a formidable number of stores opened their doors on Thanksgiving Day, bucking with tradition and not waiting until Black Friday to begin their sales. This pushed an increasing number of consumers to shop earlier than they would normally, essentially making Black Friday a two-day event. But do more people hitting the stores on Thanksgiving Day also increase the number of online sales? You betcha.

This year, one out of every four dollars spent online on Black Friday came from a mobile device, making Black Friday the biggest mobile shopping day of the year. Consumers not only used their mobile devices to compare product prices but also to shop while passing the time waiting in lines. Online sales at big-box retailers on Thanksgiving Day this year were 48% higher than Thanksgiving sales last year, while sales on Cyber Monday were only 13% higher. In fact, Thanksgiving Day has so far seen the highest year-over-year growth in online shopping for these merchants.

This trend is already causing some to predict the end of Cyber Monday as we know it; whether that will actually happen is yet to be determined. At the same time, this year’s Cyber Monday set a new record for online sales in a single day ($1.98 billion) and was the pinnacle of the season for all online retailers except big-box stores. What’s more, as brick-and-mortar stores become increasingly packed (and dangerous) on Thanksgiving weekend, more people are happy to stay at home, avoid the crowds, and on shop online.

So what do you think? Will Cyber Monday retain its dominant position as the biggest online shopping day of the year, or will showrooming and earlier Thanksgiving sales ultimately turn it into just another Monday?