The Border League was the name of two 20th century circuits in North American minor league baseball.
The first, also known as the Eastern Michigan League, was a Class D minor league in 1912 and 1913 at the Canada–US border. It was composed of five teams from Michigan and one from Windsor, Ontario. This six-team league never really got off the ground, playing a minimal 35 game schedule. The league lost one Michigan team that disbanded in 1913. This action helped cause the league's downfall. There was no known effort to organize the league in 1914.
The name was revived for a post-World War II Class C circuit that operated from 1946 through 1951 before shutting down. It was represented by nine cities, five from across the Canada–US border (four from Ontario and one from Quebec) and four from the state of New York. The four New York, teams, along with the Kingston, Ontario, squad were able to make the full run. The Ottawa Senators entry won three of the league's six titles.
The league proved to be a good solid competitive group for the first five years. Attendance was good, the league drew over 1,600,000 fans the first five years before finally disbanding on July 16, 1951.