In the 36 years since the Postal Reorganization Act was signed, technological advances have both improved the operations and services offered by the Postal Service and increased competition and customer expectations. A decade of prosperity in the 1980s, with a concomitant growth in mail volume, was followed by slower economic growth in the 1990s. Bankruptcies, consolidations, and restructuring of markets reduced the flow of business mail. In 1991, overall mail volume dropped for the first time in 15 years. The following year, volume rose only slightly, and the Postal Service narrowly avoided the first back-to-back declines in mail volume since the Great Depression. In an effort to address financial challenges and hold rates steady, in 1992 the Postal Service created a new organizational structure that replaced 5 regions and 73 field divisions with 10 areas and 85 districts.

Total mail volume began to grow again and, from 1992 through 2000, reached record levels. Then, in 2001, the Postal Service again saw a slight drop in total mail volume compared to the previous year. The 9/11 terrorist attacks on the World Trade Center buildings caused a tragic loss of human lives and rippled out to affect many areas. One was to intensify recessionary effects on the mailing and advertising industry. In 2002, total mail volume dropped to 202.8 billion pieces, down nearly five billion pieces from the previous year. Volume began to rise again in 2004 largely because of growth in Standard Mail. In 2005, for the first time, the volume of Standard Mail exceeded that of First-Class Mail. However, First-Class Mail continued to generate more revenue than any other class of mail.

In 2006, the Postal Service sorted and delivered more than 213 billion pieces of mail, about 40 percent of the world’s total mail volume and more than any other postal administration in the world.