What did nativists groups believe would happen if European ethnic groups continued to immigrate to the United States after World War I?

The Anglo ideal would disappear.

Explanation:

After World War I, nativists groups in U. S started to fear that if European ethnic groups continued to immigrate to the United States after, their anglo ideal and culture would disappear.

With increase in immigration from Europe after the end the World War I, the native-born Americans of European lineage felt threatened with the multiplicity of European languages, cultures, and religions increasing in the U. S.

In order to preserve their own culture and language, the nativists started numerous protests for new immigration policies. Subsequently, the Emergency Immigration Act of 1921 was introduced. For the first time, it put certain restrictions on European immigration in U. S.

The National Origins Act of 1924 was further introduced to restrict southern and eastern European immigrants. The political unrest in Russia after the end of the first World War led many eastern Europeans to migrate to U. S and other countries.