In an interview with Felix Salmon after the Democratic debate, Bernie Sanders discussed, among other things, his ideas for setting up a system of postal banking:
"If you are a low-income person, it is, depending upon where you live, very difficult to find normal banking. Banks don’t want you. And what people are forced to do is go to payday lenders who charge outrageously high interest rates. You go to check-cashing places, which rip you off. And, yes, I think that the postal service, in fact, can play an important role in providing modest types of banking service to folks who need it."
It’s something Sanders alluded to in a 2014 Wall Street Journal op-ed...
In fact, Sanders’s idea is quite sensible. “Postal banking”—which just means that post offices run savings accounts, cash checks, and perform other basic financial services—is common in most of Asia and Europe, and only about 7 percent of the world’s national postal systems don’t offer some bank-like services. Postal banking is a really good way to reach people who haven’t had access to standard savings accounts. One estimate figures that more than 1 billion people have used post offices for making deposits.
The reason why this would be so useful in the U.S. is that somewhere between 20 and 40 percent of the population has to rely on check-cashing or payday-lending services, which in some places charge usurious rates that send people into spirals of recurring debt.
How would postal banking work?
The basic idea of modern postal banking is a public bank offering a wide range of transaction services, including financial transactions, remittance, savings accounts, and small lending. These institutions would remain affordable because of economies of scale and because of the existing postal infrastructure in the U.S. Plus, in the absence of shareholders, they would not be driven to seek profits and could sell services at cost.
According to The Atlantic, there was a postal-savings system just like that in the US between 1910 and 1967.
Of course it's almost impossible to imagine that such a system could successfully be revived today. It's way too sensible, it would reinvigorate a government institution that the right wing is trying to destroy, and it doesn't extract blood from the 99 percent for the benefit of the financial elites. So probably no can do.