• by Gavin O'Malley , Staff Writer @mp_gavin, June 8, 2016

While mobile media users are nothing if not unpredictable, Snapchat appears positioned to hog much of their time through at least 2020.

This year alone, Snapchat will grow its domestic user base by 27.2%, according to a fresh forecast from eMarketer. That should far exceed the average growth rate of 16% for all mobile messaging services.

If accurate, that will bring Snapchat’s domestic user base to 58.6 million by the end of the year -- exceeding Twitter’s 56.8 million U.S. users, and Pinterest’s 54.6 million users. (Stateside, Facebook Messenger should maintain a comfortable lead with 105.2 million users.)

By 2020, meanwhile, Snapchat is on track to add 26.9 million users -- or about double that of Twitter and Pinterest.

What’s Snapchat’s secret?

It’s fun, according to eMarketer principal analyst Cathy Boyle. “In a world in which there is an app for nearly everything, Snapchat has cut through the clutter by injecting fun back into social sharing," Boyle explains in the new report.

Specifically, Boyle is referring to “the short-lived nature of [Snapchat’s] messages, the highly visual interface and the features that enable users to get creative with the images they share, and tailor them to specific locations or events.”

Not surprisingly, these fun features appeal to a younger audience. Stateside, Snapchat’s biggest user base is between 18 and 24 years old -- with that age range representing 34% of its user base, this year. Those between the ages of 25 and 34 should represent 27% of Snapchat’s domestic user base, this year.

Yet the surest sign of Snapchat’s future success is its increasing popularity with consumers under the age of 12. This year, that age segment will grow 42.9%, eMarketer expects.

Snapchat is also benefiting from young people’s preference for private conversations over public sharing, according to Boyle.

“This desire is particularly strong among millennials and younger consumers who don't have strong ties to the traditional social networks," she explains.