The Pew Research Centre survey found 54 percent of US Internet users now post original pictures or videos online, up from 46 percent last year.
And 47 percent repost images or videos they discover online, the survey found.
Much of this growth came from people using smartphone apps like Instagram or Snapchat, according to Pew researchers.
This survey found that 92 percent of Americans own a cell phone and 58 percent own a smartphone. Some 18 percent of cell phone owners use Instagram and nine percent use Snapchat to share images or videos.
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"This all adds up to a new kind of collective digital scrapbook with fresh forms of storytelling and social bonding."
Women are more active sharers than men, according to the survey: Some 59 percent of online women post photos and videos they have taken themselves, compared with 50 percent of men.
Likewise, 53 percent of women share some of the content they found elsewhere, compared with 42 percent of men.
Among those in the 18-29 age group, 81 percent have uploaded original content and 68 percent have reposted photos or videos.
"A lot of photo- and video-sharing is happening on social media, where women are historically more likely to be users," said Duggan.
"In terms of mobile, young people have always been early and eager adopters of new apps and platforms for sharing," she added.