A new book entitled How the Other Half Banks by Mehrsa Baradaran makes a great argument for why we need a postal banking system. The book explains how economic inequality in this country is caused largely by unequal credit. A significant portion of the population has been deserted by the banking system and is consequently forced to use payday lenders and check-cashing services to cover emergency expenses and pay for necessities. The best solution to the problem, argues Baradaran, is postal banking.
"The post office has branches in many low-income neighborhoods that have long been deserted by commercial banks," writes Baradaran in her NYT piece. "And people at every level of society have a certain familiarity and comfort in the post office that they do not have in more formal banking institutions."
(Order the book on Amazon and have the Postal Service deliver it.)