"progressive labor reformers embraced the minimum wage for its power to exclude as well as to uplift. The minimum wage would, more efficiently than the literacy test, target the inferior races of southern and eastern Europe by identifying inferiority not with illiteracy but with low labor productivity—the inability to command a minimum wage. [Paul] Kellogg's race hierarchy could not have been plainer. A minimum wage for immigrants, he said, would 'exclude [Angelo] Lucca and [Alexis] Spivak and other 'greeners' from our congregate industries,' reserving American jobs for 'John Smith and Michael Murphy and Carl Sneider.' . . .
"Some minimum wage advocates, such as Sidney Webb and John A. Ryan (author of the Minnesota minimum wage law), claimed that firms' labor costs would not increase, because higher wages would make workers become more productive. . . . But such efficiency-wage claims—the idea that wages were more the cause than the consequence of labor productivity—were half-hearted and exceptional. Indeed, both Webb and Ryan acknowledged that a minimum wage would cause some workers to lose their jobs, namely, those whose services were [(often for reasons grounded in racial inferiority)] worth less than the minimum rate. . . .
"The more conservative American economists . . . opposed the minimum wage on these grounds [(the grounds that 'the state would have to care for the workers idled by minimum wages')]....
"[But] The many left progressives who advocated the minimum wage, among them Father John Ryan, Charles Henderson, Matthew B. Hammond, Henry A. Millis, Henry R. Seager, Arthur T. Holcombe, and Albert B. Wolfe, agreed that the minimum wage would throw the least productive employees out of work or prevent their employment in the first place. But these reformers saw the removal of the less productive not as a cost of the minimum wage but as a positive benefit to society. Removing the inferior from work was not a regrettable outcome, justified by the higher wages for other workers. Removing the inferior from work benefited society by protecting American wages and Anglo-Saxon racial integrity.
"By pushing the cost of unskilled labor above its value, a minimum wage worked on two eugenic fronts. It deterred immigrants and other inferiors from entering the labor force, and it idled inferior workers already employed. The minimum wage detected the inferior employee, whether immigrant, female or disabled, so that he or she could be scientifically dealt with. . . .
"So identified, the inferior workers could be returned to their homes (in the case of mothers not otherwise deficient) or brought under the surveillance of the state—institutionalized, segregated in rural colonies, or even sexually sterilized. . . ."
Thomas C. Leonard, Illiberal reformers: race, eugenics & American economics in the Progressive Era (Princeton: Princeton University Press, 2016), 159-160 (but the relation of Progressive-Era minimum-wage advocacy to racism is stressed here and there throughout the book).