Twitter Fastest-Growing Mobile Audience, Up 75%

Among top social networking services, Twitter had the fastest-growing U.S. mobile audience for the three months ending in August, up 75% to 13.4 million.

LinkedIn was a close second, growing 69% to 5.5 million -- followed by Facebook, up 50% to 57.3 million, according to a new comScore report. In addition to the biggest U.S. mobile audience, Facebook also has the largest worldwide, at more than 350 million. Twitter's mobile growth should get another boost through the service's integration into the latest version of Apple's mobile operating system, iOS 5. The new iPhone 4S running the upgraded software sold a record 4 million units in its opening weekend. The comScore study found the social-networking population on mobile devices had increased 37% to 72 million in the last year ending in August. That’s equal to about 31% of all U.S. mobile users ages 13 and over. Even more significant: the number of people who access a social networking or blog on a daily basis has grown 58% in the last year to 40 million, or about 17% of mobile customers.