• Smartphones have emerged as the fastest-growing platform for online shopping this holiday season, for both browsing and purchasing.
  • They were dominant in shopping on Thanksgiving and are now on track to dominate Cyber Monday as well.
  • Their omnipresence and ease of use are most likely contributing factors.

Cyber Monday is here, and workers across America are heads-down at their desks, shopping on their phones.

The event is on track to become the biggest online sales day in US history, according to an early estimate from Adobe Analytics. As of 10 a.m., online sales had already totaled $840 million, an increase of 17% over last year.

Smartphones are one of the biggest drivers of that growth, responsible for 44.6% of site visits and nearly 30% of revenue generated. Site traffic from phones increased 21% over last year, while revenue generated from phones increased 41% – a growth record.

Part of this is because everyone keeps their smartphones on them at all times – but it’s also because shopping experiences have been refined through apps and integration with mobile-wallet services like Apple Pay.

More Cyber Monday shopping "will be happening on smartphones ... where smoother buying experiences through auto-fill capabilities are helping drive the growth we see in mobile," Tamara Gaffney, the head of Adobe Analytics' strategic insights engagement group, said in a prepared statement on the data.

For example, Apple Pay helps users avoid entering any personal or delivery information, allowing them to make a purchase immediately with just a thumbprint or face scan.

Most retailers have undergone pains to make their app experiences more streamlined as well, reducing the number of steps it takes to get from the shopping basket screen to the order confirmation screen.

Smartphones are also contributing to sales growth on Thanksgiving, accounting for 46% of all retailer traffic, according to Adobe - an increase of more than 15% over last year. At the same time, traffic from tablets and desktops decreased, making mobile the most popular option for Thanksgiving shopping for the first time.