She began her career with the
U.S. Postal Service (USPS) in 1986 as a
letter carrier in
Lancaster, Pennsylvania. She subsequently worked as a delivery and collection supervisor, a processing plant manager in
Reading and the
Lehigh Valley in Pennsylvania, and a district manager in
Springfield, Massachusetts. Brennan stepped away from the USPS for a year to study as a
Sloan Fellow at the
Massachusetts Institute of Technology. Following that hiatus, she served as manager of field support and integration and manager of operations support for the Northeast area. In May 2005 she was named vice president for the Northeast area, where she coordinated and integrated processing and distribution, transportation and delivery operations in that region. Brennan was then named vice president of Eastern Area Operations, putting her in charge of postal operations in the states of Pennsylvania, Ohio, West Virginia, Delaware, Kentucky,
Central and
South Jersey,
Western New York and parts of Virginia and Indiana. In December 2010, she was named
chief operating officer and executive vice president of the USPS. In 2012, she began shutting down mail-handling facilities because of budget cuts brought on by less mail and congressionally-mandated pension-funding rules. On November 14, 2014, the U.S.
Postal Service's Board of Governors voted to appoint Brennan postmaster general to succeed
Patrick R. Donahoe, who was set to retire in February 2015. In May 2018, the
Washington Post reported that President
Trump personally pushed her to double the rates on
Amazon and other firms. On October 16, 2019, Brennan announced in a statement that she would be retiring upon fulfilling her five-year commitment as Postmaster General. However, on January 6, her retirement was delayed until a successor could be found. ==Awards and honors==