NEW YORK (BLOOMBERG) - Black Friday hit a record US$7.4 billion (S$10.1 billion) in US online sales as many shoppers spent the day clicking instead of lining up to buy.

It was the second biggest US online sales day ever, behind 2018 Cyber Monday's US$7.9 billion, according to a survey of 80 of the top 100 US online retailers from Adobe Analytics.

Shoppers increasingly favour buying online from the start of the holiday season, rather than waiting for Cyber Monday as they may have a few years ago.

That's in part as they transition to purchasing via mobile devices from using computers - often at the office after the holiday weekend.

Purchases made by smartphone on Friday accounted for US$2.9 billion in sales, the most ever.

"With Christmas now rapidly approaching, consumers increasingly jumped on their phones rather than standing in line," said Adobe analyst Taylor Schreiner.

Overall it remained unclear the percentages of sales online versus in stores this holiday weekend.

Yet some shoppers still prefer the Black Friday in-store experience, which is sometimes a family hunting-and-gathering expedition after Thanksgiving festivities.

About 6 per cent more people visited stores this year, according the International Council of Shopping Centres.

For example, the Atlantic Terminal Mall Best Buy in Brooklyn sold out of Apple's iPhone 11 and iPhone 11 Pros on Friday and had lines stretching the length of the store as shoppers picking up Microsoft's Xboxes and Nintendo Switches among other big ticket items.

One out of five dollars this holiday season will be spent between Thanksgiving Day and Cyber Monday, according to Adobe figures, which are similar to estimates provided by Salesforce.

Cyber Monday sales are poised to outshine 2018's record by 19 per cent.