1933-34: Quadrangular League forms with Dartmouth, Harvard, Princeton and Yale.
1941-42: Army joins Quadrangular League, which is renamed Pentagonal League.
1946-47: Army leaves Pentagonal League.
1947-48: Brown joins Pentagonal League.
1950-51: Tri-State League forms with Clarkson, Colgate, Middlebury, Rensselaer, St. Lawrence and Williams.
1951-52: Midwest Collegiate Hockey League (MCHL) forms with Colorado College, Denver, Michigan, Michigan State, Michigan Tech, Minnesota and North Dakota. Colgate leaves Tri-State League.
1952-53: Williams leaves Tri-State League.
1953-54: MCHL is renamed Western Intercollegiate Hockey League (WIHL).
1955-56: Pentagonal League is renamed Ivy League.
1958-59: WIHL teams play as independents after the league disbands. Cornell joins Ivy League.
1959-60: WIHL teams reform as Western Collegiate Hockey Association (WCHA). Middlebury leaves Tri-State League.
1961-62: Eastern College Athletic Conference (ECAC) forms an informal, one-division, 28-team league that includes future Division I members American International, Army, Boston College, Boston University, Brown, Clarkson, Colgate, Connecticut, Cornell, Dartmouth, Harvard, Massachusetts, Merrimack, New Hampshire, Northeastern, Princeton, Providence, Rensselaer, St. Lawrence and Yale.
1964-65: American International, Connecticut, Massachusetts, Merrimack and New Hampshire leave ECAC’s top division. Tri-State League is renamed Independent College Athletic Conference (ICAC).
1965-66: Minnesota-Duluth joins WCHA.
1966-67: New Hampshire joins ECAC.
1967-68: Pennsylvania joins ECAC and Ivy League.
1969-70: Wisconsin joins WCHA.
1971-72: Central Collegiate Hockey Association (CCHA) forms with Bowling Green, Ohio, Ohio State and Saint Louis. Notre Dame joins WCHA.
1972-73: Lake Superior State joins CCHA. ICAC dissolves