| No. | Year | Location | Chairman | Secretary |
| 1 | 1934 | Lincoln, NE | T.A. Kiesselbach | H.M. Tysdal |
| 2 | 1934 | Washington, DC | A.J. Pieters | H.M. Tysdal |
| 3 | 1935 | St. Paul, MN | H.L. Westover | H.L. Westover |
| 4 | 1936 | Madison, WI | R.A. Brink | H.M. Tysdal |
| 5 | 1937 | Chicago, IL | R.A. Brink | H.L. Westover |
| 6 | 1938 | Manhattan, KS | H.M. Tysdal | H.L. Westover |
| 7 | 1939 | New Orleans, LA | H.M. Tysdal | H.L. Westover |
| 8 | 1940 | Ft. Collins, CO | L.F. Graber | H.L. Westover |
| 9 | 1942 | St. Louis, MO | L.F. Graber | H.M. Tysdal |
| 10 | 1946 | Logan, UT | J. W.Carlson | H.M. Tysdal |
| 11 | 1948 | Lincoln, NE | C.O. Grandfield | H.M. Tysdal |
| 12 | 1950 | Lethbridge, Canada | T.M. Stevensen | A.S. Aamodt |
| 13 | 1952 | Raleigh, NC | R.P. Murphy | A.S. Aamodt |
| 14 | 1954 | Davis, CA | O.F. Smith | H.O. Graumann |
| 15 | 1956 | St. Paul, MN | C.P Wilsie | H.O. Graumann |
| 16 | 1958 | Ithaca, NY | C.H. Hanson | H.O Graumann |
| 17 | 1960 | Saskatoon, Canada | J.L. Bolton | C.H. Hanson |
| 18 | 1962 | Davis, CA | E.H. Stanford | C.H. Hanson |
| 19 | 1964 | Lafayette, IN | R.L. Davis | C.H. Hanson |
| 20 | 1966 | University Park, PA | H.L. Carnahan | C.H. Hanson |
| 21 | 1968 | Reno, NV | W.R. Kehr | C.H. Hanson |
| 22 | 1970 | Urdana, IL | R.R. Hill, Jr. | C.H. Hanson |
| 23 | 1972 | Ottawa, Canada | D.H. Henrichs | C.H. Hanson |
| 24 | 1974 | Tucson, AZ | Dale Smith | C.H. Hanson & D.K. Barnes |
| 25 | 1976 | Ithaca, NY | M.S. Peterson | D.K. Barnes |
| 26 | 1978 | Brookings, SD | M.D. Rumbaugh | D.K. Barnes |
| 27 | 1980 | Madison, WI | E.L. Sorensen | D.K. Barnes |
| 28 | 1982 | Davis, CA | B.A. Melton | D.K. Barnes |
| 29 | 1984 | Lethbridge, Canada | R. R. Kalton | D.K. Barnes |
| President | Executive Secretary | |||
| 30 | 1986 | Minneapolis, MN | B.P. Goplen | J.H. Elgin, Jr. |
| 31 | 1988 | Beltsville, MD | W.J. Knipe | J.H. Elgin, Jr. |
| 32 | 1990 | Pasco, WA | D.R. Viands | J.H. Elgin, Jr. |
| 33 | 1992 | Atlanta, GA | J.B. Moutray | J.H. Elgin, Jr. |
| 34 | 1994 | Guelph, Canada | G.R. Bauchan | J.H. Elgin, Jr. |
| 35 | 1996 | Oklahoma City, OK | M. McCaslin | J. H.Elgin, Jr. |
| 36 | 1998 | Bozeman, MT | R. Michaud | G.R. Bauchan |
| 37 | 2000 | Madison, WI | M. Peterson | G.R. Bauchan |
| 38 | 2002 | Sacramento, CA | J. Bouton | G.R. Bauchan |
| 39 | 2004 | Quebec, Canada | S. D. Stratton | G.R. Bauchan |
| 40 | 2006 | StPaul/Minnapolis, MN | Craig Sheaffer | G.R. Bauchan |
|
41 | 2008 | Dallas/Fort Worth | Jonathan Reich | G.R. Bauchan |
| 42 | 2006 | Boise, ID | JoAnn Lamb |