Surveying the current “winter of our discontent,” one cannot but wonder what turned political differences into polarization. If we take the Sixties as the starting point, then the story might run something like the following. John F. Kennedy beat Richard Nixon in the presidential election of 1960 by a razor thin majority. However, the Kennedy Administration pursued no divisive polices. Abroad it remained within the mainstream of Cold War foreign policy. At home, it kept the Civil Rights movement at arm’s length and could not muster legislative support for any other major initiatives.
The assassination of Kennedy brought Lyndon Johnson to the White House. Johnson seized the opportunity to shift government policy at home and abroad. Formed by his youthful encounter with poverty and injustice, and a determined supporter of the New Deal, Johnson sought to “complete” the New Deal to address the needs of a different time. Johnson won passage of the Civil Rights Act (1964), then crushed his Republican rival in the 1964 election. Secure in victory and backed by a powerful shift to the left in Congress, Johnson’s legislative program created the “Great Society” structures. Many of these are with us still.
Catastrophically, however, to win election, Johnson had closed off Republican charges that Democrats were soft on Communism by using the Tonkin Gulf incident (or non-cident) to begin committing American ground troops to combat roles in South Vietnam.
Furthermore, no one in Washington foresaw the huge social upheaval when the “Baby Boom” passed through the Sixties. “Sex and drugs and rock-and-roll,” demonstrations in the streets and on campuses, and the further development of the Civil Rights movement demanded a response. Many Democrats embraced these causes, while many Republicans reacted against them. (In California, the backlash made Ronald Reagan—a former Goldwater supporter—governor and a polarizing national political figure.) The Vietnam War poured fuel on the fire. Then the Pentagon Papers (1971) and Watergate (1972-1974) created a distrust of Washington. That distrust fed a longing for “outsiders”: Carter, Reagan, Clinton, Obama, Trump.
These events set the pattern as policy issues have divided Americans. Abortion, gun control, gay rights and marriage equality, forced busing for school integration and affirmative action, drug policy, taxation, and welfare all became embattled. There is something to be said on both sides of most of these issues, but now no one is listening to the other side.
What made each of these issues so bitterly divisive has been the conflict between federal and state power. Most of the Bill of Rights was “incorporated” during the Sixties, while the Warren Court delivered a series of other decisions that rocked state preferences. Republicans have opposed this universalizing of rights on the grounds that it amounts to an imposition of Democratic beliefs on Republicans by court decisions and executive actions. The courts themselves are as embattled as the rest of us. Except those who have checked out in disgust.
 For a contrary view to what follows, see: Kevin Kruse and Julian Zelizer, Fault Lines: A History of the United States since 1974 (2019).
 Julian Zelizer, “The Fierce Urgency of Now”: Lyndon Johnson, Congress, and the Battle for the Great Society (2015). Marvelous book. Excellent scholarship, but written for the “intelligent general public.”
 The case of Roy Moore in Alabama is illustrative. Allegations of sexual misconduct dogged Moore and caused many Republicans to sit out the election, but many other Republicans voted for Moore because his opponent supported “choice”—which is, in their minds, “baby murder.”