Smartphone sales in the US grew 21% in the three months to February, and 45.4 million American now own a smartphone.
ComScore, which tracks sales and use of mobile phones, said Blackberry maker RIM was the leading mobile smartphone platform in the US, with a 42.1% share of smartphone subscribers, up 1.3% on the previous three months. Apple was second with 25.4%, down 0.1%, followed by Microsoft at 15.1%, down 4%.
The big winner was Google's Android, rising from 4.8% to 9.0%.
ComScore said 234 million Americans aged 13 and older were mobile subscribers, Motorola was the most popular handset maker, with 22.3% of the market. LG ranked second with 21.7%, and Samsung third with 21.4 %. Nokia was fourth with 8.7%, and RIM fifth with 8.2%.
The most popular applications were text messaging (64.0%), browsing (29.4%) and downloading apps (27.5%). Access to social networking sites or blogs continued to grow, rising 2.9% to 18.0%, it said.