YouTube, which had 83 million unique visits, was the second most popular mobile app with US adults age 18 and older.
Google Play was third (72 million UVs), followed by Google Search (70 million), Pandora (69 million), Google Maps (64 million), Gmail (60 million), Instagram (46 million), Apple Maps (42 million), and Yahoo Stocks (42 million).
Most mobile app engagement came from only a few categories, with social networking, games, and radio accounting for nearly half of the total time spent on mobile apps in June.
Apple iPhone owners used their smartphone apps for nine more hours more on average than Android users in June. The median iPhone owner also earns 40% more than the median Android phone owner ($85,000 vs. $61,000).
However, Android did have a larger base of users: It ranked as the top smartphone operating system in June with 83.8 million US smartphone subscribers, 16.4 million more than Apple's iOS platform. Android also had more active app users than iOS (76.1 million vs. 62.6 million).
About the research: The report was based on June 2014 data from mobile users in the United States age 18 and older.