Progressivists saw how the exploitation of immigrants was a key factor in existing structures of economic and political inequality. They knew that if the immigration question could be adequately addressed, then significant strides would be made in furthering the cause of Progressivism. To that end, Progressivists advocated measures designed to assimilate immigrants into American society. They believed that if newcomers were restricted to ethnic ghettoes, without the opportunity to take their place in mainstream society, then they were ripe for exploitation by capitalists and machine politicians alike.
For the most part, Progressivists were opposed to large-scale immigration, as they felt that it encouraged the kind of economic exploitation and political corruption they were fighting against. They were also not free from widespread prejudices towards those newcomers whose religion or ethnicity made it harder for them to assimilate.
Such prejudice found expression in a number of legislative acts during the Progressive Era, such as the Immigration Literacy Act of 1917, which severely restricted the influx of immigration by insisting on the passing of an English literacy test, and the Quota Act of 1921, which eliminated immigration from all Asian countries.
Although the 1920s is often seen as representing the negation of Progressivism, the Progressive Era actually helped to establish the foundations for a more restrictive government approach towards the issue of immigration.