The correct answer is Civil rights act
This act prevented states from implementing voter limiting acts which were designed to segregate African-American people. It also had a set of laws regarding segregation in general, as in segregation in employment, education, public life, and any other similar things. Later they added the Housing act which also protected equal housing.
It was maybe the lack of British loyalists in the country, the lack of troops in the country, and France and Spain's involvement in the revolution<span />