U.S. Postal Service Primer: Answers to Key Questions About Reform Issues, Report to Congressional Committees [open pdf - 3MB]
From the Highlights: "USPS [United States Postal Service] is the largest postal service in the world, delivering an estimated 49 percent of all mail sent globally and playing a critical role in the nation's communications and commerce. Congress designed USPS to be a self-sustaining entity that, like a business, would cover its operating costs primarily with revenues from selling certain products and services. However, starting in fiscal year 2007, USPS's expenses began exceeding its revenue. This has led to total net losses of $87 billion from fiscal years 2007 through 2020, and $188 billion in total unfunded liabilities and debt as of the end of fiscal year 2020. GAO [Government Accountability Office] created this primer to help explain why USPS's financial condition has deteriorated so dramatically and to discuss some options for addressing the situation."
Government Accountability Office: http://www.gao.gov/