There were a total of 39 delegates and 11 fraternal delegates, representing 21 states and 2 organizational districts.
California
Cameron H. King -- (San Francisco)
Connecticut
Martin F. Plunkett -- (Wallingford)
District of Columbia
J. Webb Richman -- (Washington)
Illinois
J. Louis Engdahl -- (Chicago)
William F. Kruse -- (Chicago)
W.F. Wenschoff -- (Mt. Olive)
Indiana
John C. Lewis -- (Elwood)
Iowa
Fred Feuchter -- (Davenport)
Kansas
Ross Magill -- (Garnett)
Kentucky
W.A. Sandefur -- (Robards)
Maryland
S.M. Neistadt -- (Baltimore)
Massachusetts
Harry Fieldman -- (Springfield)
Henry Puranen -- (Fitchburg)
George E. Roewer Jr. -- (Boston)
Michigan
Lazarus S. Davidow -- (Detroit)
Missouri
G.A. Hoehn -- (St. Louis)
New Hampshire
George Cheatham -- (Manchester)
New Jersey
Milo C. Jones -- (Newark)
New York
Morris Hillquit -- (New York) -- who was substituted for by Julius Gerber, afternoon of June 28.
Algernon Lee -- (New York)
Charles W. Noonan -- (Schenectady)
Benjamin Orr -- (Bronx)
Charles Solomon -- (Brooklyn)
H.D. Wilcox -- (Elmira)
Northwest Organizational District
Otto Newman -- (Portland, OR)
Ohio
Jacob Ojala -- (Ashtabula)
John G. Willert -- (Cleveland)
Oklahoma
H.F. Stanwood
Pennsylvania
Joseph E. Cohen -- (Philadelphia)
Rose Coleman -- apparently a substitute for Jane W. Tait of Pittsburgh
Birch Wilson -- (Reading)
Rhode Island
Peter Marcus -- (Providence)
Southern Organizational District
H.F. Flanagan -- (Atlanta, GA)
Utah
O.A. Kennedy -- (Ogden)
West Virginia
C.W. Kirkendall // apparently a substitute for S.J. Gordon of Charleston//
Wisconsin
C.A. Boorman -- (Wisconsin Rapids)
Victor L. Berger -- (Milwaukee) -- who was substituted for by Edmund T. Melms, afternoon of 6/28.
William Coleman -- (Milwaukee)
Daniel W. Hoan -- (Milwaukee)
Wyoming
A. Carlson -- (Story)
National Executive Committee (non-voting)
Otto Branstetter
William Brandt
William Henry
Bertha Mailly
Edmund Melms
-- FRATERNAL (NON-VOTING) DELEGATES --
Bohemian [Czech] Federation
Charles Kolarik
German Federation
Adolph Dreifuss
Finnish Federation
G. Makela
Italian Federation
Girolamo Valenti
Yugoslav [Slovenian] Federation
Frank Petrich
Young People's Socialist League
Morris Novik (New York)
source: "Minutes of the National Convention, Socialist Party," in The Socialist World [Chicago], v. 2, no. 6/7 (June-July 1921), pg. 24.