A map line is a line that appears on a map to indicate a certain feature. An isotherm is a line on a map connecting points of equal temperature. An isobar is a line on a map connecting points of equal atmospheric pressure. A CONTOUR is a line on a map connecting points of equal elevation. A ROUTE is a line on a map connecting two or more places. A ROAD is a line on a map connecting two or more places, usually for the purpose of transportation. A STREET is a line on a map connecting two or more places, usually within a city or town.