Automated Clearing Houses (ACHs) process both private payments, such as automatic deposits to wage-earners bank accounts, and public payments, such as direct deposits of Social Security stipends. The 12 regional Federal Reserve Banks provide ACH services to banks around the United States. Between 2015 and 2018, ACH payments grew by 6 percent a year and the value of remote general-purpose payments nearly equaled that of in-person payments.

Aside from the Federal Reserve, why is there an oligopoly operating ACH systems in the United States instead of a large number of smaller ACH companies?