sentences:  The new freeway was marked as I-81 beginning in 1959.Construction on the portion of I-81 south of US 40 began in 1962 to fill a gap between the portion of I-81 in Maryland and the portion of the Interstate completed between WV 9 near Martinsburg and US 11 southwest of Williamsport in West Virginia.MD 144's bridge over I-81 was constructed in 1963 once the relocated US 40 opened.