The social network's app, which had 85,574,000 unique visitors in December, overtook the Google Maps app after September, which, as ComScore notes, coincides with Apple removing Google Maps from iOS 6. But Google may make a comeback now that its new, and popular, Maps app for iOS 6 is available.
ComScore VP of Industry Analysis Andrew Lipsman writes in a blog post that Apple's Google Maps lockout was "largely responsible for the position swap," and that the mapping app "has been clawing its way back the past few months after getting reinstated on iOS 6."
Google still claimed five of the top six U.S. mobile apps at the end of 2012. Google Maps came in second to Facebook at 74,631,000 users, followed by Google Play, Google search, Gmail, and YouTube.
Even with Google's dominance in the number of visitors, Facebook has always been No. 1 when it comes to how much time users spend on the app. ComScore's numbers show that Facebook's mobile app accounts for 23 percent of time spent on apps. This is separate from Instagram's 3 percent stake. All of Google's apps combined account for 10 percent of time spent. This means more than 1 out of every 3 minutes spent on mobile apps is spent on Facebook or on a Google app, ComScore points out.
Keeping an eye on their mobile numbers is important to both Facebook and Google -- and any tech company, really -- as more users choose to use their mobile devices over desktop computers. After going public last year, Facebook, especially, has faced Wall Street pressure to make money off its growing mobile audience.
Correction, 1:34 p.m. PT: The numbers reported by ComScore are in the millions. The text has been changed to reflect this.