Answer is the rise of Imperialism.
The moral majority has declined because it was based in christian values. Now that more and more people are atheist, the idea of deeply rooted morals is lessening. Though this is what America wants, it honestly is not good for the country, as we all know that morals are a very good thing to have, and letting good morals guide a country is a very good thing.
Increased number of women working in industries
This implied the sudden weakening of the traditional family hence less children which resulted to decreased population in the northern cities whose lifeline was industries and pay job as source of income. more and more women bore less children.
