A timeline of NCAA Division I college hockey conferences. The season indicates when the change took effect.
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.
1973-74: Army leaves ECAC’s top division. Ohio leaves CCHA to drop hockey. Ohio State leaves CCHA to become independent.
1974-75: Vermont joins ECAC.
1975-76: Ohio State, Western Michigan join CCHA.
1977-78: Northern Michigan joins CCHA.
1978-79: Ferris State joins CCHA. Pennsylvania leaves ECAC and Ivy League to drop hockey.
1979-80: Saint Louis leaves CCHA to drop hockey. Maine joins ECAC, which splits into three regions (East, West, Ivy).
1980-81: Miami joins CCHA.
1981-82: Michigan, Michigan State, Michigan Tech, Notre Dame leave WCHA to join CCHA.
1982-83: Illinois-Chicago joins CCHA.
1983-84: Notre Dame leaves CCHA to drop to club status (returns to varsity as an independent in 1984-85).
1984-85: Hockey East Association forms with Boston College, Boston University, Maine, New Hampshire, Northeastern and Providence, all from ECAC, and Massachusetts-Lowell. Army joins ECAC. Michigan Tech, Northern Michigan leave CCHA to join WCHA.
1985-86: Great West Hockey Conference (GWHC) forms with Alaska, Alaska-Anchorage, Northern Arizona and U.S. International.
1986-87: Northern Arizona leaves GWHC to drop hockey.
1988-89: Alaska, Alaska-Anchorage leave GWHC to become independent. U.S. International leaves GWHC to drop hockey.
1989-90: Merrimack joins Hockey East.
1990-91: St. Cloud State joins WCHA.
1991-92: Army leaves ECAC to become independent. Union joins ECAC.
1992-93: Kent State, Notre Dame join CCHA. Alaska joins CCHA as an affiliate member.
1993-94: Alaska-Anchorage joins WCHA.
1994-95: Kent State leaves CCHA to drop hockey. Massachusetts joins Hockey East.
1995-96: Alaska joins CCHA as a full member.
1996-97: Illinois-Chicago leaves CCHA to drop hockey.
1997-98: Northern Michigan leaves WCHA to join CCHA.
1998-99: Metro Atlantic Athletic Conference (MAAC) forms with American International, Canisius, Connecticut, Fairfield, Holy Cross, Iona, Quinnipiac and Sacred Heart.
1999-2000: College Hockey America (CHA) forms with Air Force, Army, Alabama-Huntsville, Bemidji State, Findlay and Niagara. Bentley, Mercyhurst join MAAC. Minnesota State joins WCHA. Nebraska-Omaha joins CCHA.
2000-01: Army leaves CHA to join MAAC. Wayne State joins CHA.
2003-04: Fairfield, Iona leave MAAC to drop hockey. MAAC becomes Atlantic Hockey Association.
2004-05: Findlay leaves CHA to drop hockey. Robert Morris joins CHA. ECAC becomes an independent affiliate of ECAC and is renamed ECAC Hockey League.
2005-06: Vermont leaves ECAC Hockey to join Hockey East. Quinnipiac leaves Atlantic Hockey to join ECAC Hockey.
2006-07: Air Force leaves CHA to join Atlantic Hockey. Rochester Institute of Technology joins Atlantic Hockey.
2008-09: Wayne State leaves CHA to drop hockey.
2010-11: CHA folds. Alabama-Huntsville becomes independent. Bemidji State joins WCHA. Niagara, Robert Morris join Atlantic Hockey. Nebraska-Omaha leaves CCHA to join WCHA.
2013-14: Big Ten forms with Michigan, Michigan State and Ohio State from CCHA, Minnesota and Wisconsin from WCHA and independent Penn State. National Collegiate Hockey Conference (NCHC) forms with Colorado College, Denver, Minnesota-Duluth, Nebraska-Omaha, North Dakota and St. Cloud State from WCHA and Miami and Western Michigan from CCHA. Alaska, Bowling Green, Ferris State, Lake Superior State and Northern Michigan leave CCHA to join WCHA. Notre Dame leaves CCHA to join Hockey East. Alabama-Huntsville joins WCHA. CCHA folds.
2014-15 (scheduled): Connecticut leaves Atlantic Hockey to join Hockey East.
Sources: League media guides, College Hockey Historical Archives