Americans used smartphone and tablet apps more than PCs to access the Internet last month -- the first time that has ever happened.

Mobile devices accounted for 55% of Internet usage in the United States in January. Apps made up 47% of Internet traffic and 8% of traffic came from mobile browsers, according to data from comScore, cited Thursday by research firm Enders Analysis. PCs clocked in at 45%.

Although total Internet usage on mobile devices has previously exceeded that on PCs, this is the first time it's happened for app usage alone.

The shift follows a freefall in PC sales, which suffered their worst decline in history last year.

Smartphone adoption, meanwhile, increased 39%, acording to research firm IDC. This trend will likely continue thanks to improved user experience on mobile apps and the expansion of high-speed 4G access, said Andrew Lipsman, vice president of marketing and insights at comScore (SCOR).

As of January, 55% of American adults had smartphones, while 42% owned tablets, according to the Pew Research Center.