Why do you think the American government passed laws limiting immigration in the 1920s?

They passed the immigration laws to stem the potential tide of immigrants that were eager to escape war torn Europe.

"The Immigration Act of 1920 limited the number of immigrants allowed entry into the United States through a national origins quota. The quota provided immigration visas to two percent of the total number of people of each nationality in the United States as of the 1890 national census. It completely excluded immigrants from Asia."