Citizenship+(David)

A grassroots Americanization movement popular before World War I influenced developments in the Naturalization Bureau during the 1920s to publish the first federal textbook on citizenship.Mass immigration resumed after the war, and Congress responded with a new immigration policy, known as the national origins quota system. Created by immigration acts of 1921 and 1924.In 1924 congress created Boarder patrol to keep illegal immigrants from becoming citizens illegally.

http://www.uscitizenship.info/ins-usimmigration-insoverview.html