東半球
A more complex quota plan, the National Origins Formula, replaced this "emergency" system under the Immigration Act of 1924 (Johnson-Reed Act), which set quotas on the number of immigrants from the Eastern Hemisphere, and effectively banned all immigration from Asia. The reference census used was changed to that of 1890, which greatly reduced the number of Southern and Eastern European immigrants. An annual ceiling of 154,227 was set for the Eastern Hemisphere.