On the evening of July 2, 1964, President Lyndon B. Johnson signed the Civil Rights Act into law. Instead of celebrating, he retreated to his bedroom, looking deeply troubled. His special assistant, Bill Moyers, found him there and asked what was wrong.
Johnson looked up and said, “I think we just delivered the South to the Republican Party for a long time to come.”
It was not modest. This precise political forecast triggered a chain of events still shaping current politics and deepening divisions. It also invites a moment of Bias Reflection on how those divides formed and persisted.
To understand the roots of polarization, the story does not begin in 1964. It starts a full century earlier.
What Is Political Polarization and Why Does History Matter?
Political polarization is the widening gap between opposing political groups in their values, policies, and increasingly their basic perception of reality. Today, that gap is at record levels. According to Gallup, the share of Americans identifying as political moderates fell to a historic low of 34% in 2024. Research from MoreInCommon found that 65% of Americans feel exhausted when thinking about politics, and only 10% say they regularly feel hopeful.
This didn’t happen overnight. It was built, one turning point at a time, across more than 160 years.
Political Polarization Before 1964: Deep Roots
Historical polarization shaped elections and rights, employing tactics such as gerrymandering and strict party loyalty. Change often came from structural shifts, not persuasion.
Civil War and Reconstruction in Political Polarization (1861–1877)
When the Civil War ended, Reconstruction was supposed to begin healing. Instead, what followed was one of the most intensely polarized eras in American political history.
According to DW-NOMINATE scores used by political scientists to chart legislative positioning across history, it is only in recent years that the level of party polarization has matched that of the Reconstruction and Gilded Age. Our current moment has a direct historical ancestor.
High polarization during Reconstruction coincided with constitutional hardball: manipulation of election credentials, egregious gerrymanders, and contested elections resolved along strict partisan lines. The parallels to today are not subtle. Most consequentially, the Jim Crow system stripped African Americans of political participation for nearly seven decades, distorting American democracy as a whole.
What eventually reduced that era’s polarization was not goodwill or better communication. It was the fracturing of the parties themselves, creating openings for bipartisan cooperation that the previous alignment had made impossible. Pew Research Center
The lesson: sometimes polarization ends not through persuasion, but through the internal collapse of the coalitions that sustain it.
Key Moments That Reshaped Polarization
Several events in modern history dramatically intensified political divides. Each turning point shifted not just policy but the way Americans see each other across party lines.
Turning Point 1: The Civil Rights Act (1964)
For most of American history, the two major parties were ideologically scrambled. Conservative Democrats dominated the South. Liberal Republicans held the Northeast. The Civil Rights Act of 1964 ended that arrangement permanently.
After Johnson signed the legislation, the parties sorted themselves along ideological lines for the first time. Barry Goldwater’s 1964 campaign lost nationally in a landslide but carried five Deep South states that hadn’t voted Republican since Reconstruction. The die was cast.
The deeper consequence wasn’t just electoral. When parties sort themselves by identity rather than policy, every policy disagreement becomes an identity conflict. That dynamic, established in 1964, is the foundation of everything that followed.
Turning Point 2: The Gingrich Revolution (1994)
For decades after the Civil Rights realignment, Congress remained a place where members of opposing parties compromised and occasionally voted together. Tip O’Neill and Ronald Reagan traded political punches during the day and shared drinks in the evening. That culture ended abruptly in 1994.
When Newt Gingrich led Republicans to a historic House majority, he brought a combat model of politics with no modern precedent. He discouraged Republican members from relocating their families to Washington, preventing the cross-party friendships that had historically softened political combat. He distributed memos coaching candidates to describe Democrats using words like “corrupt,” “sick,” and “traitors.”
Congress shifted from an institution of negotiation into a theater of permanent conflict. According to Pew Research, members of both parties holding very unfavorable opinions of the opposing party are at record highs as of 2022, a trend that accelerated sharply from the mid-1990s onward.
Turning Point 3: The Iraq War Decade (2001–2008)
In the days after September 11, 2001, the Senate voted 98 to 0 to authorize military force. President Bush’s approval briefly reached 90%. The country was, for a moment, facing the same direction.
Within two years, that unity had shattered. The decision to invade Iraq became the most polarizing foreign policy debate in a generation. But what made this era uniquely damaging wasn’t just the disagreement. Americans weren’t divided only about whether to go to war. They were divided about whether weapons of mass destruction existed, about what counted as evidence, about who was telling the truth.
This decade introduced what political scientists call partisan epistemology: not just different values, but different facts. That pattern proved nearly impossible to reverse.
Turning Point 4: The Obama Years (2008–2016)
Barack Obama’s election as the first Black president was, for millions of Americans, a profound symbol of progress. For others, it represented the acceleration of demographic change that felt threatening.
Political scientist Michael Tesler documented a striking shift: racial attitudes became strongly predictive of white Americans’ partisan preferences, not just on racial issues, but on healthcare and economic policy. The Tea Party movement channeled genuine economic anxiety alongside cultural displacement into a new strain of Republican politics. The birther movement became the first major fabricated political narrative to gain mainstream traction.
What this period revealed is a dynamic that operates independently of any individual politician. When demographic change accelerates, political anxiety follows. How leaders respond to that anxiety determines the polarization that results.
Turning Point 5: Social Media (2010–Present)
Every previous turning point reshaped who was polarized and why. This one changed the speed at which polarization spreads.
Research shows polarization began accelerating precisely with the widespread adoption of smartphones and social media around 2010. The mechanism is counterintuitive: social media doesn’t just trap us in bubbles of agreement. It systematically surfaces the most extreme version of the other side and rewards our outrage with engagement and social approval.
The scale of damage is measurable. The share of adults who believe there is at least some common ground between the parties declined by an average of 12 percentage points between 2023 and 2024 alone. Not over a decade. In a single year.
History Doesn’t Repeat, But It Rhymes
LBJ’s prediction on the night of July 2, 1964, was right. But it wasn’t destiny. At every turning point in this history, there were people who chose differently: legislators who voted across party lines, leaders who refused to weaponize division, citizens who kept the conversation going across the lines their culture was drawing.
They didn’t stop the tide. But they slowed it. And in a democracy, slowing the tide matters because it keeps the possibility of something better alive.
Understanding this history transforms today’s crisis from something that feels random and inevitable into something that was built, which means it can, at least in theory, be rebuilt differently.
Ready to explore what’s actually working today? Read our next guide: Empathy in Action: Community Initiatives That Are Bridging the Divide.
Frequently Asked Questions
What is political polarization?
The process by which political groups move further apart in values, beliefs, and identity, to the point where compromise becomes politically and psychologically costly. It exists in two forms: ideological polarization (different policy positions) and affective polarization (mutual hostility regardless of policy).
When did the political divide in America start?
The roots reach back to Reconstruction after the Civil War, when polarization matched today’s levels by historical measures. Modern sorting accelerated after 1964, intensified through the Gingrich Revolution, deepened during the Iraq War era, and reached new intensity with social media after 2010.
Who started the political divide?
No single person or party created today’s polarization. It emerged from structural forces: racial realignment after 1964, combative strategies pioneered by figures like Newt Gingrich, the collapse of shared media, and algorithms that reward outrage over nuance.
What are the main causes of political polarization?
Partisan identity sorting along racial and cultural lines, institutional incentives rewarding confrontation over cooperation, the fragmentation of shared media into partisan ecosystems, and social media algorithms that amplify extremity.
What are the effects of political polarization?
Legislative gridlock, declining civic trust, the normalization of democratic backsliding, the spread of misinformation, and a political culture where compromise is seen as betrayal.
Why is political polarization a problem?
Because democracy requires a minimum of shared reality and mutual legitimacy to function. When citizens cannot agree on basic facts, or when opponents are perceived as enemies rather than fellow citizens, the mechanisms of democratic governance break down.