The Carolinas are two states in the south-east of the United States, sitting one above the other on the Atlantic side: North Carolina and South Carolina. People say “the Carolinas” when they mean the pair as one region — the food, the coast, the hills, the accent — rather than naming each state. There used to be a single English colony called Carolina; it later split, which is why the two names still share the same second half. In casual American talk you will also hear “the Carolinas” in weather reports and in travel: a storm moving up the Carolinas, a road trip through the Carolinas. It is a place name in the plural, always with the. One state alone is North Carolina or South Carolina, not “a Carolina” in careful talk, though “Carolina” does appear in team names and songs.