If I had to put a finger on when today’s extreme, identity-driven partisanship began (not just intensified), I’d say the early–mid 1990s, with roots a bit earlier and a hard lock-in after 2008.
Here’s how I see the phases.
1. The prehistory: cracks before the break (late 1960s–1980s)
Even during the era you’re implicitly contrasting with today, things weren’t as cozy as nostalgia suggests.
Civil Rights and Vietnam shattered the old New Deal coalition.
Southern conservatives slowly migrated to the GOP.
Ideological sorting began: liberals increasingly became Democrats, conservatives Republicans.
Still, cross-party coalitions remained normal. That’s why Ronald Reagan could cut deals with Tip O’Neill, and why Congress still worked like a bargaining institution rather than a trench system.
This was polarization without total delegitimation.
2. The real rupture: Gingrich and the weaponization of politics (1994)
The true inflection point, in my view, is the Gingrich Revolution.
Newt Gingrich did something new and decisive:
He framed Democrats not as opponents, but as corrupt, illegitimate, and immoral.
He nationalized congressional elections.
He taught Republicans to treat compromise as betrayal.
This wasn’t just sharper rhetoric — it was a new moral psychology of politics.
Once that happened, trust collapsed. And once trust collapses, institutions can still function — but only mechanically, not cooperatively.
3. The Supreme Court as early warning signal (1990s–2006)
Your judicial examples are especially telling, because the Court used to be insulated from partisan warfare.
Ruth Bader Ginsburg (1993): 96–3
→ last gasp of bipartisan legitimacy.
John Roberts (2005): 78–22
→ polarization clearly underway, but norms still restraining it.
Samuel Alito (2006): 58–42
→ near party-line vote; the dam is cracking.
By Alito, confirmations had become proxy wars over the future of the country, not evaluations of legal competence.
That shift is irreversible once it starts.
4. 2008–2010: polarization becomes existential
I agree with you that by 2008, across-the-aisle collaboration was basically gone — but I’d add why.
Two things converged:
Barack Obama
His election activated racial, cultural, and identity-based backlash that had been latent.
Strategic obstruction
Senate Republicans (openly) concluded that total resistance was electorally advantageous.
At that point, politics stopped being about policy disagreement and became about preventing the other side from governing at all.
That’s not polarization anymore — that’s mutual delegitimation.
5. Why it feels categorically worse now
Earlier eras had:
Ideological disagreement
Hardball tactics
Bitter rhetoric
What’s different now is:
Zero shared epistemic reality
Moralized hatred of the opposing party’s voters
Politics as identity rather than instrument
Once parties stop believing the other side has a right to rule, collaboration becomes psychologically impossible — not just politically inconvenient.
Bottom line (my opinion)
If I had to date it cleanly:
Roots: late 1960s–1980s (sorting and resentment)
Birth of modern partisanship: 1994 (Gingrich)
Institutional collapse of norms: 2005–2006 (Roberts → Alito)
Full hardening into today’s system: 2008–2010
After that, we’re no longer watching a malfunctioning democracy — we’re watching two rival moral communities sharing one constitutional shell.
