Here's how historians periodize it by general consensus:
First Party System: 1792-1824. Federalists (Adams, Hamilton) vs. Democratic-Republicans (Jefferson, Madison).
Era of Good Feelings: 1824-1828. Federalists gone, no new challengers yet emerged.
Second Party System: 1828-1852. Democrats (Jackson) vs. Whigs (Clay).
Third Party System: 1850s-1890s. Democrats vs. Republicans.
Fourth Party System: 1896-1932. Democrats vs. Republicans, Republicans dominant.
Fifth Party System: 1932-disputed. Democrats (New Deal Coalition) dominant.
Sixth Party System: Disputed-disputed -- at any rate, beginning no later than 1980 and lasting until quite recently. Republicans (Reagan Revolution) dominant.
What next?
First Party System: 1792-1824. Federalists (Adams, Hamilton) vs. Democratic-Republicans (Jefferson, Madison).
Era of Good Feelings: 1824-1828. Federalists gone, no new challengers yet emerged.
Second Party System: 1828-1852. Democrats (Jackson) vs. Whigs (Clay).
Third Party System: 1850s-1890s. Democrats vs. Republicans.
Fourth Party System: 1896-1932. Democrats vs. Republicans, Republicans dominant.
Fifth Party System: 1932-disputed. Democrats (New Deal Coalition) dominant.
Sixth Party System: Disputed-disputed -- at any rate, beginning no later than 1980 and lasting until quite recently. Republicans (Reagan Revolution) dominant.
Seventh Party System
Mark D. Brewer and L. Sandy Maisel speculate that "in the wake of Donald Trump's 2016 presidential victory, there is now strengthening debate as to whether we are entering a new party system as Trump fundamentally reshapes the Republican party and the Democratic party responds and evolves as well."[13] Some also argue that it started in 2008, 2012, or 2020.
Proponents of the Sixth Party system starting in the late 1960s argued that if the Seventh Party System has not started yet, the Sixth Party System would be the longest party system in United States history, breaking the 40-year-long Third Party System's previous record.
Possible dealignment period
One possible explanation for the lack of an agreed-upon beginning of the Sixth Party System is that there was a 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. Ronald Inglehart and Avram Hochstein identify the time period of the American dealignment as 1958 to 1968.[14] Although the dealignment interpretation remains the consensus view among scholars, a few political scientists argue that partisanship remained so powerful that dealignment was much exaggerated.[15]
What next?