Article I, Section 8, Clause 7: The Postal Clause

To establish Post Offices and post Roads;

This clause gives Congress the power to designate post offices and postal routes. The power to appropriate land for actual construction of offices and roads was recognized by the mid-19th century, but federal highway funding has generally been regarded as an aspect either of national defense (for moving armed forces) or as part of the general spending power attributed to Congress under Clause 1.

Congress is also empowered to regulate what can be sent through the mail, and to establish criminal penalties for interfering with the mail. Congress also has passed laws forbidding mailing of obscenity or of using the mail for gambling purposes, but SCOTUS rulings in the 20th century (aimed mostly at restrictions on political mailings) have established the principle that Congress cannot restrict free expression in mailings.

The Postal Clause served two purposes. First, it helped give effect to the aspiration in the Preamble of “form[ing] a more perfect Union” by improving interstate communications. Second, it provided a needed source of revenue for the young government. Ironically, the Postal Service became a financial liability even before the Internet, and is likely to remain such.