Note H — APPENDIX IV. Membership Statistics.

In this and some of the following columns more than one figure has been included in years for which varying estimates were found. The sources for column 4 are as follows: Proceedings 2nd I. W. W. Convention, p. 60; Report of the I. W. W. to the Stuttgart International Socialist Congress, Industrial Union Bulletin, Aug. 10, 1907, p. 4; Bulletin New York State Department of Labor, no. 67 ("International trade union statistics"), p. 3; Louis Levine, "The development of syndicalism in America," Political Science Quarterly, vol. xxviii, p. 478 (Sept., 1913); Vincent St. John's testimony before U. S. Commission on Industrial Relations (Final Report and Testimony, vol. ii, p. 1456; Weekly People, Dec. 9. 1916, p. 1, col. 3).