The term "state line" refers to the boundary between two states. There are a number of synonyms for this phrase including border, boundary, frontier, dividing line, junction, boundary marker, geo-border, territorial line, demarcation line, and boundary line. Each synonym has its own nuances and subtle differences, but they all refer to the place where one state officially ends and another begins. Whether you are traveling from one state to another or simply marveling at the geographical and political boundaries that define our country, the state line is an important and often fascinating landmark.