always used before a noun
: relating to or connecting different states : existing or occurring between states especially in the U.S.
an interstate highway
interstate commerce/transportation
plural interstates
US
: a major highway that connects two or more states : an interstate highway
You'll get there quicker if you take the interstate.
Interstate 90
Cite this Entry
“Interstate.” Merriam-Webster.com Simple Definition, Merriam-Webster, https://www.merriam-webster.com/simple/interstate. Accessed 21 Jun. 2026.
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