Already bigger than Twitter with 300 million monthly users globally, Instagram is on track to reach 100 million users in the U.S. alone within three years.
According to eMarketer's latest research, the photo-sharing app's user base in the U.S. grew 12 percent last year, which amounted to 48 million users.
Those numbers are particularly eye-popping given that by next year, Instagram's U.S. followers will be more than half the size of parent company Facebook's North American audience. In January's fourth-quarter report, Facebook said that it had 208 million U.S. and Canada users.
"The simplicity of the app is what is most appealing," said eMarketer principal analyst Debra Aho Williamson, in a statement. "Instagram has stayed true to its core mission—delivering beautiful imagery and videos—while other services, such as Snapchat, have loaded on lots of new features."