ATHENS, Ga. — PEOPLE like to complain about banks popping up like Starbucks on every corner these days. But in poor neighborhoods, the phenomenon is quite the opposite: Over the past couple of decades, the banks have pulled out.

Approximately 88 million people in the United States, or 28 percent of the population, have no bank account at all, or do have a bank account, but primarily rely on check-cashing storefronts, payday lenders, title lenders, or even pawnshops to meet their financial needs. And these lenders charge much more for their services than traditional banks. The average annual income for an “unbanked” family is $25,500, and about 10 percent of that income, or $2,412, goes to fees and interest for gaining access to credit or other financial services.

But a possible solution has appeared, in the unlikely guise of the United States Postal Service. The unwieldy institution, which has essentially been self-funded since 1971, and has maxed out its $15 billion line of credit from the federal government, is in financial straits itself. But what it does have is infrastructure, with a post office in most ZIP codes, and a relationship with residents in every kind of neighborhood, from richest to poorest.

Last week, the office of the U.S.P.S. inspector general released a white paper noting the “huge market” represented by the population that is underserved by traditional banks, and proposing that the post office get into the business of providing financial services to “those whose needs are not being met.” (I wrote a paper years ago suggesting just such an idea.) Postal banking has a powerful advocate in Senator Elizabeth Warren, Democrat of Massachusetts, who has publicly supported the plan.