The act had negative economic effects. Economists have argued that both innovation and employment were negatively affected by the restrictions. In a 2020 paper, the economists Petra Moser and Shmuel San demonstrated that the drastic reduction in immigration from Eastern and Southern European scientists led to fewer new patents, not only from immigrants but also from native-born scientists working in their fields.[56] Even the mass migration of unskilled workers had been a spur to innovation, according to a paper by Kirk Doran and Chungeun Yoon, who found "using variation induced by 1920s quotas, which ended history's largest international migration" that "inventors in cities and industries exposed to fewer low-skilled immigrants applied for fewer patents."[57] Nor did US-born workers benefit, according to a 2023 study in the American Economic Journal. Farming, a sector of the economy highly reliant on migrant labor, shifted towards more capital-intensive forms of agriculture, whereas the mining industry, another immigrant-reliant industry, contracted.[58]
Again, read the Wikipedia article, which is only a starting point for anyone actually interested in all this.