Understandings and views of freedom change over time, and sometimes it is difficult to speak of a "prevailing" concept of freedom, because the concept is identity-based as well. By the end of the twentieth century, individual, personal freedoms were paramount for many Americans.
Late in the twentieth century, this was expressed in many different ways. Reagan-era conservatism was steeped in the rhetoric of individualism and focused on the ability of a person (or a business) to work and spend and invest their money in any way they saw fit. Government interference and regulation was portrayed as a violation of these freedoms.
On the other hand, many people historically deprived of opportunity—women and minorities in particular—demanded that the government establish regulations in order to level the societal playing field. For them, only the government could protect their fundamental freedom as an economic actor. For many people, freedom consisted in equality of access to education and other institutions. Without access, they argued, there could be no meaningful freedom. So, at the end of the twentieth century, a longstanding debate continued placing individual liberty against a freedom based on equality of opportunity. Freedom at the end of the twentieth century was, as it has always been, a contested proposition.