The U.S. banking system has reached an important crossover point in which the number of weekly mobile bankers now equal those who use the branch, according to a report from the San Francisco-based Javelin Strategy & Research.

The shift to mobile is happening faster than anticipated, but not without some annoyance from users, and profound, fundamental changes in banking, Javelin reported. "The Rise of the Mobile First Consumer – and What that Means for Banking," revealed that as a result of the adoption of smartphones and tablets, almost one in every four primary bank customers currently claim to be "mobile first," that is, they primarily use a mobile device to access their checking account. This represents a shift of almost 53 million consumers in just four years.

Mobile-first bankers include those who primarily bank by smartphone or tablet using a mobile app or mobile website. In terms of numbers, 56 million American adults now consider themselves to be mobile first.