It's automated. It doesn't mean continuously operating. I'd recommend listening to this planet money episode[1] where they describe how the ACH came to be. It

It's automated. It doesn't mean continuously operating. I'd recommend listening to this planet money episode[1] where they describe how the ACH came to be. It's called automated, because it's a step up from the original method of payment processing between banks: handing physical slips of paper between each other. [1] http://www.npr.org/sections/money/2013/10/04/229224964/episode-489-the-invisible-plumbing-of-our-economy http://www.npr.org/sections/money/2013/10/04/229224964/episo...