As with any periodization, opinions differ on when the Sixth Party System may have begun, with suggested dates ranging from the late 1960s to the Republican Revolution of 1994.

"[7] Writing in 2020, political scientists Mark D. Brewer and L. Sandy Maisel argue "[i]t seems safe to state that the sixth American party system featured strong divisions between Republicans and Democrats, rooted in cleavages based on social class, social and cultural issues, race and ethnicity, and the proper size and scope of the federal government.

"[11] The Princeton Encyclopedia of American Political History dates the start in 1980, with the election of Reagan and a Republican Senate.

[12] Arthur Paulson argues that "[w]hether electoral change since the 1960s is called 'realignment' or not, the 'sixth party system' emerged between 1964 and 1972.

Non-whites, who predominantly vote Democratic, have grown as a share of the population, and previously Republican-leaning secular college-educated whites have moved to the left.

One possible explanation for the lack of an agreed-upon beginning of the Sixth Party System is the brief period of dealignment immediately preceding it.

Dealignment is a trend or process whereby a large portion of the electorate abandons its previous partisan affiliation without developing a new one to replace it.

[19] Harris and Tichenor argue: "At the level of issues, the sixth party system was characterized by clashes over what rights to extend to various groups in society.

The initial manifestations of these clashes were race-based school desegregation and affirmative action, but women's issues, especially abortion rights, soon gained equal billing.

"[20] New voter coalitions included the emergence of the "religious right", which is a combination of Catholics and Evangelical Protestants united on opposition to abortion and same-sex marriage.

The old system of using county caucuses and state party conventions to pick the delegates largely gave way in 1972 to primaries, thanks to the reforms proposed by the McGovern–Fraser Commission for the Democrats.

The new-style national convention was rarely the site of bargaining and dealing, but instead became a ratification ceremony run by the winner in the primaries.

[26] In 2016 and 2020, Bernie Sanders financed presidential campaigns heavily from small-dollar donations generated online.