The United States Postal Service's (USPS) constitutional mandate

"The United States Postal Service's (USPS) constitutional mandate is outlined in the Postal Clause, which is Article I, Section 8, Clause 7 of the Constitution ... Establish post offices and post roads: Congress has the power to establish post offices and post roads, including designating existing buildings and routes.

Designate mail routes: The USPS has the authority to designate mail