GAO Report on USPS volume, performance and financial changes since the onset of the COVID-19 pandemic
"COVID-19 profoundly affected the U.S. Postal Service's mail delivery operations. Letters and total mail declined in 2020, but packages hit record levels. According to USPS, its on-time performance was significantly affected when record package levels combined with employee absences due to COVID-19 -- especially in December 2020. COVID-19 also drove up costs, with USPS reporting increased expenses for increased use of leave and personal protective equipment. Although 2020 revenues increased, the cost increases led to an additional $100 million in net losses for the postal service."