Since the ratification of the US Constitution in 1788, there have been historic realignment elections about every 36 years. These elections were revolutions that reset the social, political and ideological battlegrounds for a generation to follow. I’m not a political scientist nor historian and may have some of this wrong, so please be patient with me.
1828: Andrews Jackson sweeps into office and the Second Party System, or the Jacksonian Era, begins with the establishment of the old Democratic Party during the Antebellum period.
1860: Abraham Lincoln and the American Civil War, or the Third Party System, with the establishment of the Republican Party. The most profound change in America, ever.
1896: William McKinley/Theodore Roosevelt and the Progressive Era, the Fourth Party System. A continuation of sustained Republican Party dominance but with new progressive ideas about taxation, women’s suffrage and labor rights countering the corrupted Gilded Age.
1932: Franklin Roosevelt and the New Deal Era, the Fifth Party System. A rebooted Democratic Party supported by organized labor that ushers in social programs like Social Security and Medicare.
1968: Richard Nixon and the current era, the Sixth Party System. The Civil Rights Era and Conservative Republican backlash that followed it.
2000, a deadlocked election signaled the nearing end of the sixth party system but 9/11 changed everything and sent the electorate into a wild pendulum swinging back and fourth between the two parties.
2002 — 2004, Republican wins followed by 2006 — 2008 with historic Democratic wins, only to be returned with 2010 Republican claw-backs, 2012 Democratic win, and 2014 Republican win.
2016 the unimaginable Donald Trump happens.
2018 and 2019 sustained Democratic waves have signaled that 2020 may be the long delayed and long sought after realignment election that ushers in a Seventh Party System.