involving and relating to the mutual relations of states especially of the United States, Pertaining to the mutual relations of States; existing between, or including, different States, Involving, existing between, or connecting two or more states, noun_ One of a national system of expressways connecting major population centers in the United States, An interstate highway, part of the United States Interstate Highway system

a major road for any form of motor transport, A main, direct public road, especially a multi-lane, high speed thoroughfare connecting major population centers, A public road or passage; a way open to all passengers, by either land or water

Plural form of center, verb_ Third-person singular simple present indicative form of center