Mobile banking user growth shows no signs of slowing at three of the nation’s largest banks.

JPMorgan now counts 18.4 million active mobile users, while Wells Fargo counts 13.7, according to data two companies released yesterday. Bank of America, which released results today, has 16.1 million users.

It was  particularly strong quarter for mobile user growth for the nation’s largest bank, in terms of mobile users. Chase grew its active mobile user base a whopping 7% over last quarter, and 23.5% on the year. Wells, meanwhile, grew its mobile users 4.6% on the quarter and 19.1%for the year.

B of A grew 3.9% on the quarter and 15% over last year.

It is commonplace for banks large and small to include mobile in their advertisements now, and Apple Pay has only accelerated that trend. But is advertising what is driving people to mobile, or is it just the convenience arising fro a particular use case, such as depositing a check with the smartphone camera?

As mobile grew at the three biggest banks in the nation, branches held steady or dropped slightly. Chase cut back slightly on its total number of branches, dropping to 5,613 from 5,636 the previous quarter. In 3Q13 the bank claimed 5,652 branches. Wells Fargo stood pat with about 6,200 stores, according to a spokesperson, while Bank of America, with 4,947 branches, shuttered 76 branches on the quarter and 296 over the past year. For B of A, that is a 6% year-over-year decline.

Bank of America CFO Bruce Thompson told analysts on the earnings call that the downsizing of the branch network was tied to the growth of mobile. “Growth in mobile as well as other self-service customer touch points has allowed us to continue to reduce our banking centers where we went below 5,000 units during the quarter, while at the same time, our customer satisfaction scores continued to improve and customer activity continues to build,” he said.

Meanwhile, there was some confusion on the mobile numbers on Chase’s earnings call yesterday, according to the transcript from Seeking Alpha:

Gerard Cassidy – RBC
You guys gave us some very good numbers on the mobile approximately usage by your customers. What’s the penetration rate of your customer base that uses that mobile app?

Marianne Lake – CFO
I mean it’s still relative to 20 something million customers in household in the 23 something like that million households in the retail sales space is still relatively low. And from recollection we’ll check the numbers for you I think is in that 2 million to 3 million range, but nevertheless…

Jamie Dimon – Chairman and CEO
Mobile is much higher than that.

Marianne Lake – CFO
Mobile is higher, okay. We’ll get back to you.

Gerard Cassidy – RBC
And then finally you guys talked about Apple Pay…

Marianne Lake – CFO
It’s 18 million.

Jamie Dimon – Chairman and CEO
It’s 18; I don’t know if that’s individuals or households — it’s a huge amount.

A huge amount indeed.

Active Mobile Users: JPMorgan Chase and Well Fargo