In fact, due to the unique structure of the USPS, government shutdowns never touch the mail delivery service.
Since the funding lapses that cause shutdowns only apply to annually-appropriated funding, permanently funded services or services funded through user fees are not affected by the shutdown. So self-sustaining programs, like the Postal Service or passport issuance , or permanently-funded programs, like Social Security , do not get caught up in the budget battle.
The USPS generates most of its own funding through the roughly $70 billion in operating revenue taken in each year from the sale of stamps, cost of shipping , and other operations.
"As an 'independent establishment of the Executive Branch of the Government of the United States,' we receive no tax dollars for ongoing operations and have not received an appropriation for operational costs since 1982," the USPS said in its annual financial filing . "We fund our operations chiefly through cash generated from operations and by borrowing from the Federal Financing Bank ('FFB'), a government-owned corporation under the general supervision of the Secretary of the Treasury."
The only consistent appropriation given to the USPS by Congress is reimbursement for low-cost postage that is given to the blind and for overseas absentee ballots.
While the USPS is spared, there are still wide-ranging effects from the shutdown as it drags into a second month. From airports to food programs to 800,000 unpaid federal workers the shutdown is starting to get real.