interstate(n = noun.artifact) interstate highway - one of the system of highways linking major cities in the 48 contiguous states of the United States;
is a kind of highway, main road

   interstate(a = adj.all) - involving and relating to the mutual relations of states especially of the United States; "Interstate Highway Commission"; "interstate highways"; "Interstate Commerce Commission"; "interstate commerce"
Antonym: intrastate

   Pertaining to the mutual relations of States; existing between, or including, different States; as, interstate commerce. Story.

   An interstate highway, part of the United States Interstate Highway system. [PJC]

interstate, adj. & n. US
--adj. existing or carried on between States, esp. of the US.
--n. a motorway, esp. crossing a State boundary.

interstate commerce, interstate commerce commission, interstate highway