This paper examines the congressional passage of the American minimum wage law, the Fair Labor Standards Act of 1938. Voting on the act is modeled as a function of the concentration of the constituencies for minimum wage legislation, North-South differentials, and legislator ideology. It is shown that the House radically altered the final content of the bill, abandoning a proposed Wages and Hours Board with discretionary powers to determine minimum wages in favor of a flat rate following the objections of several interest groups; North-South divisions over the bill had little influence over congressional voting; and the influence of constituent groups increased relative to legislators' ideology as the bill became an important election issue.