DCHP-1 Online
base line † 
1 in government surveys, the east-west line that functions as a starting point for the parallel lines demarcating blocks, townships, etc.
See also: block proof line township
- On the Prairies, base lines run east and west, 24 miles apart, moving northwards, beginning at the 49th parallel; in Old Ontario (Upper Canada) the base lines tend to parallel the St. Lawrence River and the shore of Lake Ontario.
2 a road that lies on or near a base line.
See also: base-line road