U.S. Constitution, Article I — The Legislative Branch, Section 9, Clause 6
No Preference shall be given by any Regulation of Commerce or Revenue to the Ports of one State over those of another: nor shall Vessels bound to, or from, one State, be obliged to enter, clear, or pay Duties in another.
Notes
Bars any regulation of commerce or revenue from giving preference to the ports of one state over those of another. Bars requiring vessels bound to or from one state to enter, clear or pay duties in another state, so ships cannot be forced to route through another state's ports.
Use as reference
Lexinter.net | U.S. Const. art. I, § 9, cl. 6 | https://laws.lexinter.net/constitution/us/article-1/section-9/clause-6