While Myspace Inc.'s business took a huge slide in the U.S. over the past year, use of rival Twitter Inc.'s social network simply exploded as visits to the site in September increased by 1,170 per cent compared to year-earlier figures, according a report released last week by Experian Hitwise, an Internet monitoring firm.

Twitter , the fourth most visited social networking site, grabbed 1.84 per cent of the U.S. market among the top 155 social networking sites in September 2009. That's a huge increase over the same month last year when the microblogging site only had 0.15 per cent of the market, Experian Hitwise said.

Market leader Facebook saw its already impressive market share increase by 194 per cent, letting it easily maintain its recently attained place atop the U.S. market. Facebook, which grabbed its 300 millionth user last month, captured 58.59 per cent of all U.S. social network visits last month, compared to 19.94 per cent the year before.

Myspace, while still easily in second place with a 30.26 per cent share of the U.S. market, saw the biggest slide year-over-year, reported Hitwise. Myspace share has plunged 55 per cent from its Sept., 2008, market leading 66.84 per cent share, according to Experian Hitwise.

Visitors to Tagged, a five-year-old social networking site, increased by 47 per cent to take third place with a 2.38 per cent share of the U.S. market last month. And myYearbook.com rounded out the top five with 1.05 per cent, 40 per cent less than last year.

Both Facebook and Twitter have been on a roll for the past year.

Online traffic tracker ComScore Inc. reported in April that the number of Twitter's U.S. visitors increased by 131 per cent between February and March of 2009. Twitter had 9.3 million visitors in March -- 5 million more than it did in February, according to ComScore.

And in June, Nielsen Co. reported that Facebook users spent 13.9 billion minutes on the site in April, a dramatic hike from the year-earlier total of 1.7 billion minutes.