NEW YORK – Surging online sales contrasted with disappointing brick-and-mortar volume as the holiday shopping season got under way.

E-commerce purchases soared 14% on Cyber Monday to a record $3 billion plus, causing websites including target.com to temporarily crash from overuse.

In-store crowds for Black Friday, by comparison, were thinner than expected. ShopperTrak estimated brick-and-mortar sales for the four-day Thanksgiving weekend at $20.43 billion, down 10.4% from 2014.

The measurement of total digital and in-store shoppers during the period marked a sea change. Roughly 103 million Americans shopped online over the weekend, exceeding the 102 million who visited stores, according to a National Retail Federation survey.

Many retailers anticipated the change, rolling out website deals early Thursday morning, hours before shoppers could access the discounts in stores. And chains including Walmart and J.C. Penney Co. offered Cyber Monday deals on Sunday, effectively turning the event into a two-day affair.

“This is truly a seminal event in American culture,” said CloudCommerce chief executive officer Andrew Van Noy. “E-commerce has now fully shifted to become the primary preference for shoppers. We have seen this coming for a long time.”

Inside stores, Thanksgiving Day, a notably controversial day for retail, grossed an estimated $1.8 billion, while Black Friday garnered around $10.4 billion, according to ShopperTrak. “This year, we saw Black Friday ads emerge before Halloween, as retailers aimed to get at the shopper’s wallet early,” said ShopperTrak chief revenue officer Kevin Kearns. “And from our data, we saw greater retail sales generated prior to the Black Friday weekend, which is a result of retailers successfully elongating the holiday season. Ultimately, while many question the ongoing relevance of Black Friday, it is still the biggest sales day of the year and signals the start of the holiday shopping season.”

Fewer visits on both days reinforced the trend of shoppers researching products ahead of time, targeting their store visits, and arriving with the intention of making a purchase, added ­Kearns. “The decrease in shopper visits on Thanksgiving Day also lends itself to the social backlash against store openings on the holiday,” he said.

On Cyber Monday however, digital spending rose by more than one-fifth over last year to $3.12 billion, marking the first time in history that one-day e-commerce volume bettered $3 billion. Mobile sales are estimated to have accounted for 27% of the total, with $838 million spent via smartphones and tablets.

Tracking by comScore found that 107.8 million Americans visited online retail properties on Cyber Monday using a desktop computer, smartphone or tablet, up 23% from last year. Amazon ranked as the most visited online retailer, followed by Walmart, eBay, Target and Best Buy.

“Despite some talk of Cyber Monday declining in importance, the day’s historic highs and continued strong growth rates confirm it is still a hugely important shopping event,” said comScore chairman emeritus Gian Fulgoni. “It comes as no surprise that Amazon led all online retail properties in Cyber Monday traffic, but several multichannel retailers such Walmart and Target also had very strong showings. Although some websites experienced unfortunate server problems on Cyber Monday that appear to have been caused by heavy mobile traffic, it’s not yet clear what the impact was for those retailers. What is clear is that the consumer economy is still healthy.”

Steve Bratspies, chief merchandising officer at Walmart U.S., said Black Friday brought the greatest integration yet of the chain’s in-store and online offerings. “Tens of millions of customers visited our digital and physical aisles to pick up video games and systems, televisions, movies and toys, many of the top items sold both on walmart.com and in stores. And they prepped beforehand — more than 25 million customers accessed store maps and the circular through our online and mobile tools for Black Friday.”

The event has been planned for more than a year, he added. “Our stores were organized, well prepared and safe, and I couldn’t be prouder of how our associates served our customers. Our registers were lit up and queue lines went smoothly.”

Walmart associates who worked in stores on Thanksgiving were rewarded with an additional 15% discount on a holiday shopping trip.