What was the main objective of the national origins act of 1924?

Restricting the new migrants from Southern Europe and Asia.

Explanation:

National origins act o 1924 was a law that restricted immigration through a system of Quotas and discrimination against immigrants from southern and eastern Europe. It excluded Asians from migrating to the US. It was a permanent policy. The quotas for migrants were decided based on ethnic identity and national origin.  It tightened the 1921  quota system, which was a temporary provision. It also set the quotas at 2 percent of each national group which was residing in the USA in 1890 and the year of census figures was moved from 1910 to 1890, it allowed to allot more quota to the old immigrants from Northwestern Europe. The south westerners received less quota.