1. Tsebelis, George and Money, Jeannette, Bicameralism (Cambridge, UK: Cambridge University Press, 1997), 45–70CrossRefGoogle Scholar.

2. Berens, Charlyne, One House: The Unicameral's Progressive Vision for Nebraska (Lincoln: University of Nebraska Press, 2005)Google Scholar.

3. Senning, John P., “Unicameralism Passes Test,” National Civic Review 33 (1944): 60–65Google Scholar; Srb, Hugo F., “The Unicameral Legislature—A Successful Innovation,” Nebraska Law Review 40 (1961): 626–33Google Scholar; Robak, Kim, “The Nebraska Unicameral and Its Lasting Benefits,” Nebraska Law Review 76 (1997): 791–818Google Scholar; Berens, One House.

4. The diffusion of most of these institutional reforms across the states has been studied extensively. On the diffusion of the citizen's initiative, see, e.g., Persily, Nathaniel A., “The Peculiar Geography of Direct Democracy: Why the Initiative, Referendum, and Recall Developed in the American West,” Michigan Law and Public Policy Review 2 (1997): 11–41Google Scholar; Bowler, Shaun and Donovan, Todd, “Direct Democracy and Political Parties in America,” Party Politics 12 (2006): 649–69CrossRefGoogle Scholar; Smith, Daniel A. and Fridkin, Dustin, “Delegating Direct Democracy: Interparty Legislative Competition and the Adoption of the Initiative in the American States,” American Political Science Review 102 (2008): 333–50CrossRefGoogle Scholar; Bridges, Amy and Kousser, Thad, “Where Politicians Gave Power to the People: Adoption of the Citizen Initiative in the U.S. States,” State Politics and Policy Quarterly 11 (2011): 167–97CrossRefGoogle Scholar. On the diffusion of the direct primary, see, e.g., Merriam, Charles E. and Overlacker, Louise, Primary Elections (Chicago: University of Chicago Press, 1928)Google Scholar; Ware, Alan, The American Direct Primary: Party Institutionalization and Transformation in the North (New York: Cambridge University Press, 2002)CrossRefGoogle Scholar; Ansolabehere, Stephen, Hansen, John Mark, Hirano, Shigeo, and Snyder, James M. Jr., “More Democracy: The Direct Primary and Competition in U.S. Elections,” Studies in American Political Development 24 (2010): 190–205CrossRefGoogle Scholar.

5. Senning, John W., The One-House Legislature (New York: McGraw-Hill, 1937)Google Scholar; Johnson, Alvin W., The Unicameral Legislature (Minneapolis: University of Minnesota Press, 1938)Google Scholar.

6. Three states (Pennsylvania, Georgia, and Vermont) had unicameral legislatures at the time of the American Founding, but all adopted bicameral legislatures by the 1830s. Johnson, The Unicameral Legislature, 32–44.

7. Berens, One House, 1–17.

8. Quoted in Senning, The One-House Legislature, 40.

9. George Norris to L. E. Williams, August 18, 1942, George Norris Collection, Library of Congress, file 15.

10. George Norris to E. D. Nolan, March 7, 1940, George Norris Collection, Library of Congress, file 15.

11. Norris to Williams; Berens, One House.

12. Senning, One-House Legislature; Rogers, James R., “Judicial Review Standards in Unicameral Legislative Systems: A Positive Theoretic and Historical Analysis,” Creighton Law Review 33 (1999): 65–120Google Scholar.

13. Nebraska, State of, Nebraska Blue Book (Lincoln, NE: State Journal, 1934)Google Scholar.

14. It also makes the post-1934 period different from other points in American history in which cameral reform was considered, such as the period between 1912 and 1916 when several unicameral initiatives made it to statewide ballots. As much research has shown, the adoption of a major institutional reform in a single state usually triggers a set of mechanisms that lead to the diffusion of that reform in other states. As will be shown, most of these mechanisms were triggered when Nebraska adopted unicameralism in 1934. For a more extensive discussion of other moments in American history in which unicameralism was considered, see Rogers, “Judicial Review Standards in Unicameral Legislative Systems.”

15. Senning, One-House Legislature.

16. “Resolved: That the Several States Should Adopt a Unicameral System of Legislation,” Topics, National Speech and Debate Association, accessed June 5, 2018, https://www.speechanddebate.org/topics/.

17. George Norris Papers, Library of Congress, boxes 15–19.

18. The twenty-two states in which constitutional amendments establishing unicameral legislatures were proposed in 1937 were Arkansas, California, Georgia, Idaho, Iowa, Kansas, Massachusetts, Minnesota, Montana, New Jersey, New Mexico, New York, North Dakota, Ohio, Oklahoma, Oregon, Pennsylvania, Rhode Island, Texas, Washington, Wisconsin, and Wyoming. Johnson, The Unicameral Legislature, 184–87.

19. Willoughby, W. F., Principles of Legislative Organization and Administration (Washington, DC: Brookings Institution Press, 1934)Google Scholar.

20. The first state to adopt merit selection of judges was Missouri, in 1940. See, e.g., Fitzpatrick, Brian T., “The Politics of Merit Selection,” Missouri Law Review 74, no. 3 (2009)Google Scholar, available at https://scholarship.law.missouri.edu/mlr/vol74/iss3/13.

21. Ware, The American Direct Primary.

22. George Norris to H. B. Porterfield, May 16, 1940, George Norris Collection, Library of Congress, file 15, box 145.

23. These states were Arkansas, Arizona, California, Colorado, Michigan, Missouri, Montana, North Dakota, Ohio, Nevada, Oklahoma, and Oregon. New York State Constitutional Convention Committee, Constitutions of the States and United States (Albany, NY: J.B. Lyon, 1938)Google Scholar.

24. Norris to Porterfield.

25. Levinson, Sandy, Framed: America's 51 Constitutions and the Crisis of Governance (New York: Oxford University Press, 2011)Google Scholar.

26. McKay, Robert B., Reapportionment: The Law and Politics of Equal Representation (New York: Simon and Schuster, 1965)Google Scholar.

27. To be sure, urban counties or cities usually enjoyed a greater number of legislators than their rural counterparts in these chambers, but the number of legislators they had was rarely proportionate to their populations.

28. Seawright, Jason and Gerring, John, “Case Selection Techniques in Case Study Research: A Menu of Qualitative and Quantitative Options,” Political Research Quarterly 61, no. 2 (2009): 294–308Google Scholar.

29. Neb. Const. of 1919, art. III, sec. V; McKay, Reapportionment: The Law and Politics, 366; Gus Tyler, “The Majority Don't Count,” The New Republic, August 22, 1955, 13–15.

30. McKay, Reapportionment: The Law and Politics, 359–60, 398. The malapportionment rankings come from Tyler, “The Majority Don't Count.” Tyler cites calculations from Henry Stoner showing that constituencies accounting for at least 40.8 percent of Nebraska's population were required to elect a majority of seats in the Nebraska House (the state's more malapportioned chamber), while 29.4 percent and 31.8 percent of the state populations could conceivably elect a majority of seats in the Missouri and Ohio Houses, respectively.

31. Senning, One-House Legislature, 45.

32. Berens, One House, 34.

33. Berens, One House.

34. “History Approves Bicameral System,” Omaha World Herald, October 17, 1934 (originally printed in Grand Island Independent); “Not a Personal Issue,” Omaha World Herald, October 23, 1934; “The Separate Ballots,” Omaha World Herald, November 5, 1934; Berens, One House, 37–38.

35. Norris Amendment Committee to George Norris, April 6, 1934, George Norris Papers, Library of Congress, file 15; Berens, One House, 37.

36. “The Why the Concession?” Omaha World Herald, October 15, 1934; “Suppose There Were Fifty,” Omaha World Herald, October 26, 1934; “Not a Personal Issue.”

37. “The State's Relief Job,” Columbus Citizen, June 26, 1937; Hal Confery, “City-Rural Aid Row Resumed in House,” Columbus Citizen, May 25, 1938; William H. Newton, “Senate Rebels as Its Leader Blocks Relief,” Columbus Citizen, June 22, 1938.

38. Maurer, David J., “Relief Problems and Politics in Ohio,” in The New Deal, Volume Two: The State and Local Levels, ed. Braeman, John, Bremner, Robert H., and Brody, David (Columbus: Ohio State University Press, 1975)Google Scholar.

39. “Cuyahoga County Demands Equal Representation,” Greater Cleveland, January 28, 1937; “The One-House Legislature,” Greater Cleveland, November 18, 1937.

40. Citizens League of Cleveland, “The One-House Legislature: Nebraska's First Experience Proves Unicameral Plan Popular,” Greater Cleveland, November 18, 1937, 2–3.

41. Lody Huml, “The Cause for the Unicameral Legislature” (unpublished manuscript), John Senning Papers, State Historical Society of Nebraska.

42. Joint Resolutions 10, 11, 16, 26, 59, Ohio House of Representatives, 92nd General Assembly of Ohio, Regular Session,1937, Bulletin of the 92nd General Assembly of Ohio, Regular Session (Columbus, OH: F.J. Heer, 1937).

43. “Ox-Cart Government,” Cleveland Plain Dealer, May 30, 1938.

44. “Our ‘One-Horse Shay,’” Columbus Citizen, April 9, 1937, 2B.

45. “Thanks to Mr. Huml,” Cleveland Press, January 26, 1937, 8.

46. “5 Unicameral Plans,” Columbus Citizen, February 2nd, 1937, 28.

47. Bulletin of the 92nd General Assembly of Ohio, Regular Session.

48. Vinton E. McVicker, “One-House League Seeks Ohio Constitution Change,” Columbus Citizen, February 17, 1937, 2A.

49. “One-House League Incorporated Here,” Columbus Citizen, April 23, 1937, 1.

50. “A Single House Legislature for Ohio,” 1938, Ohio League of Women Voters Collection, Ohio History Connection, box 2.

51. “Prof. King Leads Unicameral,” Akron Beacon-Journal, May 14, 1937, 41; Gene Fiske, “Three Petitions Fail from Lack of Signers,” Toledo Times, June 1947.

52. “Proposed One-House Legislature Scored,” Columbus Citizen, February 17, 1938.

53. Norman H. Ford to George Norris, March 26, 1938, George Norris Collection, Library of Congress, file 15, box 144.

54. Gene Fiske, “Three Petitions Fail from Lack of Signers,” Toledo Times, June 1947.

55. Johnson, The Unicameral Legislature, 185.

56. Ray Buchan to George Norris, April 28, 1938, George Norris Collection, Library of Congress, file 15.

57. F. Taylor Bryant Jr. to President of the League of Women Voters of St. Louis, October 17, 1941, Papers of the League of Women Voters of St. Louis, State Historical Society of Missouri, box 86; “50 to 75-Seat Legislature Is Proposed,” St. Louis Star-Times, April 24, 1942, evening edition.

58. Promotional Material of the Crusaders of Missouri, N.D., Stratford Lee Morton Constitutional Convention Papers, State Historical Society of Missouri (hereafter cited as SLMCC MSS).

59. James W. Miller to Unnamed Recipient, January 30, 1943, SLMCC MSS.

60. “50 to 75-Seat Legislature Is Proposed.”

61. Harry Wilson, “Unicameralism May Be Ruled Off Ballot,” St. Louis Globe-Democrat, July 10, 1942.

62. “A Solution to the Senatorial Redistricting Problem,” SLMCC MSS, folder 90.

63. John Senning to Stratford Lee Morton, October 30, 1943, SLMCC MSS, folder 189.

64. “Proposal No. 11 in the 1943 Constitutional Convention of Missouri,” October 7, 1943, SLMCC MSS.

65. “Unicameral Plan for Legislature Rejected, 13 to 2,” St. Louis Post-Dispatch, January 12, 1944, 1.

66. In letters to other supporters of unicameralism, Morton frequently argued that the most effective argument in its favor among convention delegates was that, if a unicameral body was good enough for the purposes of writing fundamental (constitutional) law, it should be good enough for the purpose of statute writing as well. See, e.g., Stratford Lee Morton to Arthur Willoughby, April 26, 1944, SLMCC MSS.

67. Morton to Willoughby.

68. Debates of the 1943–1944 Constitutional Convention of Missouri (Jefferson City, MO, 1944), University of Missouri–Kansas City School of Law, http://dl.mospace.umsystem.edu/umkclaw/islandora/object/umkclaw%3A56, 5446.

69. Journal of the 1943–1944 Constitutional Convention of Missouri (Jefferson City, MO, 1944), July 18–19.

70. Stratford Lee Morton to Tilghman Cloud, February 15, 1944, SLMCC MSS folders 180–83.

71. “Stockard Ordered to Accept Unicameral Vote Petitions,” Jefferson City Post-Tribune (Jefferson City, MO), August 7, 1944, 1.

72. “The Letter of the Law,” St. Louis Star-Times, July 10, 1944, 12; John T. Stewart, “One-House Legislature Confounds Its Enemies and Proves Efficiency,” St. Louis Star-Times, December 6, 1943, 13; John T. Stewart, “Labor Is Firmly Backing Nebraska's One-House System,” St. Louis Star-Times, December 8, 1943, 19.

73. William P. Elmer, “Congressman Elmer Expresses His Opposition to the Unicameral Amendment Number Two,” Houston Herald (Houston, MO), October 26, 1944, 2.

74. Curtis A. Betts, “One-House Move May Delay End of Convention,” St. Louis Post-Dispatch, September 28, 1944, 6.

75. Debates of the 1943–1944 Constitutional Convention of Missouri, 7604.

76. Ibid., 7628

77. Ibid., 7607

78. Ibid., 7624

79. Journal of the 1943–1944 Constitutional Convention of Missouri, September 27, 1944.

80. “One-House Proposal to Stay on November Ballot—Stockard,” Daily Capital Times (Jefferson City, MO), October 5, 1944.

81. “Election Skulch,” Pleasant Hill Times (Pleasant Hill, MO), November 17, 1944.

82. Under the initiative petition rules in place prior to the adoption of the new constitution, organizers were required to turn in signatures to the Missouri secretary of state no later than four months prior to an election in order to qualify for its ballot. Mo. Const. of 1875, art. IV, sec. LVII (amended November 3, 1908). Under the constitution adopted in 1945, organizers were required to turn in signatures no later than six months prior to a November election, thus depriving them of the ability to canvass during the summer. Mo. Const. of 1945, art. III, sec. L.

83. These states were Arkansas, Colorado, Maine, Massachusetts, New Hampshire, New York, South Dakota, Virginia, Washington, and Wisconsin. Data are from Tyler, “The Majority Don't Count.”

84. Senning, The One-House Legislature, 41.

85. Interestingly, South Dakota was the first state in the country to adopt the citizen initiative in 1898, but it only did so for the purpose of enacting statutes. The Mount Rushmore State did not give its voters the ability to initiate changes to the state constitution until 1974.

86. Ralph O. Hillgren, “One Amendment to Be Voted on at 1938 Election,” Daily Argus-Leader, March 5, 1937.

87. “Limit on Debt, Unicameral Bills Are Introduced,” Daily Argus-Leader, January 19, 1935; “Unicameralism Plan Faces Uncertain Future at Pierre,” Daily Argus-Leader, January 24, 1935.

88. “New Legislative Setup Scheduled for Vote in 1935,” Daily Argus-Leader, March 9, 1935.

89. “Problem of Apportionment is Studied by Committee, Preliminary Bill Offered,” Daily Argus-Leader, January 11, 1937; Hillgren, “One Amendment to Be Voted on at 1938 Election.”

90. States are considered to have low levels of malapportionment if capturing a majority in both of their legislative chambers necessitated winning seats accounting for at least 40 percent of the state population. States considered sites of significant unicameralism efforts met one of the following three benchmarks: (1) an organized interest group working on behalf of unicameralism existed in them across multiple years; (2) a unicameralism referendum was voted upon by the state electorate; or (3) a governor made unicameralism one of his signature issues and worked actively on its behalf.

91. Baker, Gordon E., Rural Versus Urban Political Power: The Nature and Consequences of Unbalanced Representation (Westport, CT: Greenwood Press, 1955)Google Scholar; Key, V. O. Jr., American State Politics (New York: Knopf, 1956); Tyler, “The Majority Don't Count”; Richard Frost, “On Derge's Metropolitan and Outstate Legislative Delegations,” American Political Science Review 53 (1959): 792–95Google Scholar. For contrary views, see, e.g., Dye, Thomas R., “Malapportionment and Public Policy in the States,” Journal of Politics 27 (1965): 586–601CrossRefGoogle Scholar; Jacob, Herbert, “The Consequences of Malapportionment: A Note of Caution,” Social Forces 43 (1964): 256–61CrossRefGoogle Scholar.

92. Ansolabehere, Stephen and Snyder, James M., The End of Inequality: One-Person, One-Vote and the Transformation of American Politics (New York: Norton, 2008)Google Scholar.

93. This idea gains support from the fact that, like the American states, most of the Canadian provinces started out with bicameral legislatures. However, over the course of the late nineteenth and twentieth centuries, all of the Canadian provinces gradually adopted unicameral legislatures. Brad Wall, “Time to Consider Abolition of the Senate,” Canadian Parliamentary Review (Winter 2013), http://www.revparl.ca/36/4/36n4e_13_wall.pdf.

94. Robert B. McKay, Reapportionment; One Man, One Vote: A Statement of Basic Principles of Legislative Apportionment (New York: Twentieth Century Fund, 1962)Google Scholar; Ansolabehere and Snyder, The End of Inequality. For a somewhat contrary view, see Dixon, Robert G., Democratic Representation: Reapportionment in Law and Politics (New York: Oxford, 1968)Google Scholar.

95. The policy diffusion literature is vast and includes studies examining diffusion across countries, American states, and localities. Some of its most important works examining diffusion across American states include Walker, Jack L., “The Diffusion of Innovation among the American States,” American Political Science Review 63 (1969): 880–99CrossRefGoogle Scholar; Gray, Virginia, “Innovation in the States: A Diffusion Study,” American Political Science Review 67 (1973): 1174–85CrossRefGoogle Scholar; Karch, Andrew, Democratic Laboratories: Policy Diffusion among the American States (Ann Arbor: University of Michigan Press, 2008)Google Scholar; Shipan, Charles R. and Volden, Craig, “The Mechanisms of Policy Diffusion,” American Journal of Political Science 52 (2008): 840–57CrossRefGoogle Scholar; Boushey, Graeme T., Policy Diffusion Dynamics in America (New York: Cambridge, 2010)CrossRefGoogle Scholar.

96. Karch, Andrew, Nicholson-Crotty, Sean C., Woods, Neal D., and Bowman, Ann O. M., “Policy Diffusion and the Pro-Innovation Bias,” Political Research Quarterly 69 (2016): 83–95CrossRefGoogle Scholar.

97. Cain, Bruce E., MacDonald, Karin, and McDonald, Michael, “From Equality to Fairness: The Path of Political Reform Since Baker v. Carr,” in Party Lines: Competition, Partisanship, and Congressional Redistricting, ed. Mann, Thomas E. and Cain, Bruce E. (Washington, DC: Brookings Institution Press, 2005), 8Google Scholar.

98. Most of the very modest efforts to advance unicameralism in the second half of the twentieth century occurred within broader efforts to write or revise state constitutions. For example, during the Alaska Constitutional Convention of 1955–1956, delegates debated and rejected an effort to make the Alaska state legislature a unicameral body. See, e.g., Ross, Jonathan S., “A New Answer to an Old Question: Should Alaska Once Again Consider a Unicameral Legislature,” Alaska Law Review 27 (2010): 258–96Google Scholar. In the early 1970s, North Dakota and Montana each held state Constitutional Conventions in which supporters of unicameralism were a very modest presence. In each state, the unicameral proposals were voted down but later presented to voters as alternatives to the convention proposals for the legislature. It does not appear that the unicameralism referenda in either state were backed by organized campaigns on their behalf. Thus, it is not surprising that they failed in both states. Grau, Craig H. and Olsen, Dale W., Voting on Unicameral Referenda in North Dakota and Montana (Fargo, ND: University of North Dakota Bureau of Governmental Affairs, 1976)Google Scholar.

99. Investigating the post-1934 unicameralism movement in these states, as well as the others listed in Table 3, is beyond the scope of this article, but the author would be delighted if other researchers would take up this challenge.