D3 MIAA formed in 1920.
https://en.wikipedia.org/wiki/Minnesota_...Conference
Carleton
Gustav Adolphus
Hamline
Macalester
Saint John's Minn.
St. Olaf
And Saint Thomas were founding members.
Concordia-Moorhead
Augsburg
Saint Mary's of Minnesota were added later in the decade.
Some of these teams appeared in the polls for football alongside the Ivy League, Big 10 and others on a weekly basis.
Tri-Normal League which became the Evergreen Conference was founded in 1920.
https://en.wikipedia.org/wiki/Evergreen_Conference
Central Washington 1920 founding member
Eastern Washington
Spokane University school closed in 1933
Western Washington
Are the founding members of the conference with Pacific Lutheran joining in 1938 and Saint Martin's joining in 1939.
Seattle U., Whitworth, Puget Sound and and British Columbia joined in the 1940s.
Kent State Normal founded their football program in 1920.
Oklahoma Sooners left the Southwest Conference to join the MVC
Phillips school closed joined the Southwest Conference
UCLA went from Independent to join the SCIAC which is now a D3 conference.
SCIAC
Cal Tech
Occidental
Pomona
Redlands
Whittier
Were the founding members.
UCLA (1920-1927), San Diego State (1926-1939), Laverne 1926-1938) and Cal. Santa Barbara 1931-1938 were other members at the time.
The Fort Worth Classic was a Bowl game where Centre defeated TCU.
Grinnell was a major college at the time who was also part of the Big 8 schools at one time and left.
Washington And Lee
Catholic
Saint John's-Maryland
Johns Hopkins
They were major at the time.
Transylvania, Chattanooga, Mississippi College (Gulf South Conference), Howard, VMI, The Citadel, Millsaps, Georgetown, Mercer, Wofford, part of what is now the Southern Conference with major schools from the SEC and ACC and members of other FBS conferences.
Richmond, Davidson, William & Mary was in the same conference with Catholic U. and them with Virginia Tech, Maryland and North Carolina.
CIAA Founded in 1912:
Founding members:
Hampton
Howard
Lincoln
Shaw
Virginia Union
Members joining:
Virginia State
Virginia U.-Lynchburg
Saint Paul's closed
North Carolina A&T
Johnson C. Smith
North Carolina Central
Morgan State
Livingstone
Bluefield State
Saint Augustine's.
Inter-Normal Athletic Conference of Wisconsin (1913-1926) Now D3 WIAC
Founding members:
Wis.-LaCrosse
Wis.-Milwaukee
Oshkosh
Platteville
River Falls
Stevens Point
Superior
Whitewater
Joining later
Stout and Eau Claire
Kansas Collegiate Athletic Conference (KCAC) NAIA founded in 1869. Formally called Kansas Intercollegiate Athletic Association
Kansas State founder
Kansas founder
Washburn founder
Baker founder
In 1902 minus Kansas and Kansas State:KCAC was the new name.
Baker
Bethany
Bethel
College of Emporia closed
Wichita State was known as Fairmont State
Friends
Kansas Wesleyan
Emporia State
Fort Hays State
Pittsburg State
McPherson
Ottawa
St. Benedict's now Benedictine
St. Mary's dropped sports
Sterling
Southwestern
Washburn
St. John's (closed)
Kansas City (closed)
Louisiana Intercollegiate Athletic Association
La. Tech
La.-Lafayette
Centenary, La.
Not sure who else was in the conference at the time.
Michigan Intercollegiate Athletic Association (MIAA) D3
Albion
Hillsdale
Olivet
Michigan State (founder)
Eastern Michigan joined later while Mich. State was there.
Kalamazoo
Alma
Adrian
Hope
Nebraska Intercollegiate Conference now known as the defunct NAIA's Nebraska College Athletic Conference
York
Peru State
Hastings
Cotner closed
Nebraska Wesleyan
Doane
Midland Lutheran
Chadron State
Wayne State
Nebraska-Kearney
Ohio Athletic Conference (OAC) founded in 1902 D3
Founders:
Case Tech
Kenyon
Oberlin
Ohio State
Ohio Wesleyan
Western Reserve
join later:
Dennison
Heidelberg
Wooster
Wittenberg
Cincinnati
Ohio
Miami
Mount Union
Akron
Baldwin Wallace
Ohio Northern
Hiram
Otterbein
Xavier
Muskingum
Marietta
Capital
Ashland
John Carroll
Kent State
Toledo
Bowling Green
Oklahoma Intercollegiate Conference (1914–1928)
Central Oklahoma
Tulsa
Southwestern Oklahoma State
Oklahoma Baptist
Oklahoma City
Phillips
East Central Oklahoma
Southeastern Oklahoma State
Northeastern Oklahoma State
Langston
There were also a lot of Independents back in those days not involved in conferences.