David Starr Jordan viewed Mexicans as an inferior race whose migration to the United States should be severely limited for eugenic purposes. 

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He described Mexicans as a "mongrel race," a mix of white and Indigenous blood that showed "few of the virtues of the European stock." To Jordan, Mexican migration to the United States was a "social problem; a menace to peace and welfare."

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Similar to his beliefs about Black Americans, Jordan argued that Mexicans were incapable of citizenship, that poor Mexican and Indigenous migrants were "teeming millions, ignorant, superstitious, and ill-nurtured, with little self-control… lacking, indeed, most of our Anglo-Saxon values."

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Like other eugenicists of his time, Jordan portrayed Mexican migration as a public health threat spreading disease to white America. “The Mexicans have brought with them," he wrote, "bubonic plague, small pox, and typhus fever.” This narrative of Mexicans as a public health fear was a common trend in eugenic thought.