During the 20th century, many groups expanded their civil rights in the US. They did so mostly by putting pressure on the government through protests and other forms of political action.
Of course, the most prominent group to get expanded civil rights was African Americans. They were the first group to really push hard for their rights. In many ways, their push for rights helped other groups, in turn, push for their own rights. Other groups that managed to expand their rights during the 20th century were women, the disabled, gays, and the elderly. All of these groups were able to put political pressure on the government to give them rights more nearly equal to those enjoyed by other Americans.