User counts for Instagram and Twitter are strikingly similar. eMarketer estimates that 43.2 million US consumers used Twitter monthly last year—or 17.6% of the total internet user population. Meanwhile, Instagram users represented 16.1% internet users. Limiting that figure to smartphone Twitter users, Twitter hit just 30.8 million in 2013; this will increase to 37.3 million in 2014, or 22.7% of US smartphone users. Both figures fall slightly below those for total Instagram users, and while Instagram activity all but exclusively takes place on smartphones (meaning Instagram’s smartphone user base could be higher than Twitter’s), it is possible for Instagram users to have an account online without accessing the service through a smartphone. As a point of reference, eMarketer pegs US smartphone Facebook users at 123.7 million this year. Read the rest at eMarketer.