According to The Next Web, Karp credited the site’s sociability for its growth. The average Tumblr blog is re-blogged nine times, said the founder, and the content is distributed through RSS, Facebook, Twitter and other social networking platforms.
“There’s the spreadable future of social media,” quipped journalist and professor Jeff Jarvis on Twitter.
That adds up to 560 million people who have viewed content on Tumblr to date. There are 249 million visitors in the U.S. alone, comprising 45% of Tumblr’s audience. Next in line are Brazil with 49 million visits and the UK with 34 million visits."