What were three major reasons that the early 1920s were a nativist time?

The old and the new came into sharp conflict in the 1920s. While many Americans celebrated the emergence of modern technologies and less restrictive social norms, others strongly objected to the social changes of the 1920s.

In many cases, this divide was geographic as well as philosophical; city dwellers tended to embrace the cultural changes of the era, whereas those who lived in rural towns clung to traditional norms.

The Sacco and Vanzetti trial in Massachusetts and the Scopes trial in Tennessee revealed many Americans’ fears and suspicions about immigrants, radical politics, and the ways in which new scientific theories might challenge traditional Christian beliefs.

While prosperous, middle-class Americans found much to celebrate about a new era of leisure and consumption, many Americans—often those in rural areas—disagreed on the meaning of a “good life” and how to achieve it. They reacted to the rapid social changes of modern urban society with a vigorous defense of religious values and a fearful rejection of cultural diversity and equality.

Nativism

Faith, fundamentalism, and science

The Supreme Court is most likely to be accused of judicial activism in cases involving:  protection of individual rights.

Writing for the conservative group, The Heritage Foundation, Elizabeth Slattery defines judicial activism as "when judges fail to apply the Constitution or laws impartially according to their original public meaning, regardless of the outcome, or do not follow binding precedent of a higher court and instead decide the case based on personal preference."

Cases involving individual rights are likely to elicit charges of judicial activism because the Constitution does not spell out each and every sort of right citizens may have.  New questions come up that were not considered or specified at the time the Constitution was written.  For instance, Roe v. Wade (1973) addressed the question of abortion and an individual's right to privacy.  Obergefell v. Hodges (2015) addressed the legality of same-sex marriage.  Both are cases of individual rights, where the Constitution did not give direct instruction on the issues at stake.  The decisions on those issues, to allow abortion and to allow same-sex marriage, both are criticized by conservatives as instances of judicial activism.