The surge into social networks is gaining pace among Americans, with Facebook dominating but with many people using multiple platforms, a study showed Monday.

A Pew Research Center survey found 73 percent of Americans over age 18 on the Internet use at least one social network -- or about 63 percent of the total adult population.

Facebook is the preferred network, used by 71 percent of online adults, or 57 percent of all American adults, according to Pew researchers.

However other platforms like Pinterest, LinkedIn and Twitter are making gains, and a growing number of people are using multiple social networks.

Pew found that 42 percent of Internet users (or 34 percent of all American adults) use two or more of the five most popular social networks.

Use of Facebook rose to 71 percent of online adults from 67 percent a year ago, the study found.

A large part of the growth for Facebook came from older Americans: Roughly 45 percent of Internet users over 65 are using Facebook, up from 35 percent in late 2012.

Four other social networks, including Facebook-owned Instagram, are battling for the number two spot for US users.

LinkedIn is used by 22 percent of online American adults and is especially popular among college graduates and those in higher income households. That is up from 20 percent a year earlier.

Pinterest usage grew sharply to 21 percent of online adults, from 15 percent a year ago. Pew said that women are four times as likely as men to be users of the bulletin-board style social media platform.

Some 18 percent of online adults use Twitter, up from 16 percent a year ago, Pew said, with adoption levels particularly high among younger adults and African-Americans.

Instagram use rose to 17 percent of online adults from 13 percent a year ago, according to the survey. Much of this growth came in the 18 to 29 age bracket and among African-Americans.

Pew found that Facebook and Instagram drew high levels of "user engagement," with a majority of users checking in on a daily basis.

Some 63 percent of Facebook users visit the site at least once a day, and 40 percent do so multiple times throughout the day.

That compares with 57 percent of Instagram users who visit the site at least once a day and 46 percent of Twitter users.

The researchers also found considerable overlap among the leading social networks. For example, 93 percent of Instagram users also use Facebook, as do 83 percent of LinkedIn members.

Some 53 percent of Twitter users also use Instagram, and 53 percent of Instagram users use Twitter, the survey found.

The report is based on telephone interviews conducted from August 7 to September 16 among 1,801 adults age 18 and older. For the total group, the margin of error is estimated at 2.6 percentage points and 2.9 points for Internet users.

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