There's no doubt about it, in the United States, Facebook is the undisputed king of social networks. In December 2015, Facebook had 21,390,733,000 US visits on both Desktop and Mobile, vastly more traffic than its 4 biggest social media competitors, Twitter, Instagram, Reddit, and Pinterest. In comparison to these competitors, Facebook takes home 78% of the traffic share, leaving 22% to the other 4 social networks.