The Collaborative International Dictionary of English v.0.48:
Old Line State \Old Line State\ n. Maryland; a nickname, alluding to the fact that its northern boundary is Mason and Dixon's line. [Webster 1913 Suppl.]WordNet (r) 3.0 (2006):
Old Line State n 1: a Mid-Atlantic state; one of the original 13 colonies [syn: Maryland, Old Line State, Free State, MD]