From Longman Dictionary of Contemporary Englishstate lineˌstate ˈline noun [countable] PGthe border between two states in the US We crossed the state line into Missouri.
Examples from the Corpus
state line• Jenkins was arrested for illegally transporting explosives across state lines.• When the train reached the New 160 Hampshire-Massachusetts state line, it stopped again.• Invariably, she is richer after meetings at her local track, Oaklawn, just across the state line in Arkansas.• Around 1920, he established a practice just across the state line in Copperhill, Tenn.• Adams wheeled around at the state line and took off at high speed for Oglala, about fifteen miles away.• Consequently, the riders were escorted to the state line where Mississippi patrol cars took over. 