The Emergency Quota Act, also known as the Emergency Immigration Act of 1921, the Immigration Restriction Act of 1921, the Per Centum Law, and the Johnson Quota Act (ch. 8, 42 Stat. 5 of May 19, 1921), was formulated mainly in response to the large influx of Southern and Eastern Europeans and successfully restricted their immigration as well as that of other "undesirables" to the United States. Although intended as temporary legislation, it "proved, in the long run, the most important turning-point in American immigration policy" because it added two new features to American immigration law: numerical limits on immigration and the use of a quota system for establishing those limits, which came to be known as the National Origins Formula.