Snapchat's mascot is a white ghost. Twitter's is a little blue bird. But in 2016, Snapchat is the one fluttering to new heights while Twitter is disappearing -- a report Wednesday forecasts Snapchat to surge past Twitter for the first time in user numbers in the U.S.

Snapchat is expected to see growth of 27.2 percent on the year, increasing its American user base to 58.6 million users in 2016, according to a forecast by eMarketer. Twitter, by comparison, is only expected to reach 56.8 million users in 2016, according to eMarketer.

These user numbers are defined by eMarketer as individuals who log into their social media account at least once a month on a consistent basis over an entire year. They are not the concrete figures given out by either of the companies, but if this forecast proves accurate, it would mark a seismic shift in the social media landscape.

"What makes Snapchat different from other mobile messaging apps -- and more-established social networks -- is the short-lived nature of the 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," said eMarketer principal analyst Cathy Boyle in a statement.

While Twitter remains a popular social network, the company's user growth has been on a never-ending plateau over the past couple of years. Twitter's leaders have been looking for ways to reach new users, but at the same time, the company has been hesitant to make any major changes to its product. The 10-year-old company, for example, only recently decided to become a little bit more flexible with its 140-character tweet limit -- a move many experts agree should've happened long ago.

Snapchat, on the other hand, has seen a meteoric rise since its early days when it was known as nothing more than a sexting app. This is due in large part to the mobile company's willingness to frequently reinvent itself and constantly introduce new features and new technologies to its users, who largely remain millennials (those 34 and younger).

Over the past year, Snapchat has embraced a new role as a mobile media giant, launching and  frequently improving a feature called Discover where users can go to get content from outlets like Buzzfeed, Comedy Central, ESPN and many others. At the same time, the company has become a major player in the world of augmented reality, introducing so-called "lenses" that let users modify their selfies with silly masks and special effects.

"Every time something new emerges, a new media giant is created. When print magazines emerged, Time magazine emerged. When cable TV emerged, cable networks took over. Now is the time for Snapchat," said Timur Daudpota, co-founder and head of product of Blurbiz, a service that lets users create vertical videos for Snapchat. "Snapchat is the natural evolution on how people view content."

Snapchat's rise and Twitter's stagnation have been reflected in their standings with their respective investors. Twitter's share price is down nearly 34 percent on the year, reaching all-time lows in May and now hovering just below $15 a share. Snapchat, meanwhile,  raised another $1.8 billion from investors last month. Snapchat is now believed to be valued around $20 billion -- that would be nearly double Twitter's market capitalization.