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

"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."

Explanation:

It gave a basic structure to the governments and documents we have today.