Samsung was the top handset manufacturer in the U.S. in July with 23.1 percent market share, while RIM led the smartphone platforms with 39.9 percent market share, according to the latest report from comScore.

For the 3-month average period ending in July, 234 million Americans used mobile devices. Device maker LG ranked second with 21.2 percent share, followed by Motorola (19.8% share), RIM (9% share) and Nokia (7.8% share.)

In the U.S. 53.4 million people owned smartphones during the three months ending in July, up 11 percent from the corresponding April period. RIM was the leading mobile smartphone platform in the U.S. with 39.3 percent share of U.S. smartphone subscribers, followed by Apple with 23.8 percent share.

Google saw significant growth during the period, rising 5.0 percentage points to capture 17.0 percent of smartphone subscribers. Microsoft accounted for 11.8 percent of Smartphone subscribers, while Palm rounded out the top five with 4.9 percent. Despite losing share to Google Android, most smartphone platforms continue to gain subscribers as the smartphone market overall continues to grow.

comScore found in July, 2 out of 3 U.S. mobile subscribers used text messaging on their mobile devices, up 1.4 percentage points compared to the prior three month period, while browsers were used by 33.6 percent of U.S. mobile subscribers (up 2.5 percentage points). Subscribers who used downloaded applications comprised 31.4 percent of the mobile audience, representing an increase of 1.6 percentage points from the previous period. Accessing of social networking sites or blogs increased 1.9 percentage points, representing 21.8 percent of mobile subscribers.