American politics and its two-party system is not a static system.
The ebb and flow of political power proceeds in fits and starts with long periods of relative stasis and brief periods of unmistakable change. It is a kind of punctuated equilibrium. Because history is mostly hindsight with huge blind spots, there is rarely much perspective in the midst of events. There are large patterns that can be discerned, dimly at first and later, usually much later, they seem unmistakable and wholly natural. Eventually, particular elections are seen as turning points in political history. At the time they are happening, it is never as clear as it later appears.
The pivot points of political change are called realignments. Realignments happen much more slowly than a historical view suggests. In the last century there have been two major realignments. The first took place around the turn of the century and culminated in the 1932 election of FDR. It began in the late 19th century with the rise of labor unions and the emergence of what was known as Progressives. The prior realignment happened around the Civil War and the formation of what is now the Republican Party. The original Progressives were social reformers and were initially aligned with the Republican Party. Collective bargaining, the eight-hour day, government social services, civil service reform, federal support for agriculture, anti-trust laws, public education and a host of other fundamental changes were Progressive innovations.
By 1912, tensions between the progressive and conservative wings of the Republican Party led to a lop-sided presidential convention in which Theodore Roosevelt's supporters were locked out. Teddy took the Progressives out of the Republican Party into a third party called the Bull Moose Party. The upshot was the election of Woodrow Wilson and a migration of the left wing of the Republican party into the Democrats. The post-war reaction against Wilson handed control back to the Republicans during the 1920's. The financial crash and resulting depression established the Liberal Democratic majority that governed from the 1930's through the Second World War and persisted until the late 1960s.
The resulting political establishment was dominated by New Deal Democrats and ushered in reforms like Social Security, the rural electrification program (with an industrial base in The Bonneville Power Administration and the Tennessee Valley Authority), federal arbitration of labor disputes, immense political power wielded by labor unions and the establishment of a highly centralized federal government. The New Deal liberals are what most people associate with the notion of Liberalism and a powerful, centralized federalism. The culmination of the New Deal social legislation was the Civil Rights Act and the end of legal disenfranchisement of racial minorities. Most popular history focuses on the New Deal election and gives insufficient attention to the role of the progressive exodus that laid the groundwork.
The next realignment is popularly known as the Reagan Revolution. Like the preceding realignment, it had roots that went much deeper than just the 1980 presidential election. The realignment began during the post-WWII reaction. The industrialization that accompanied the Second World War brought to the fore the social tensions of Jim Crow segregation. This was reflected by the migration of sizable numbers of blacks from the Deep South into the industrial Midwest and to a lesser extent to the Northeast and West Coast. The US had just fought a global war against foes who promoted extreme racial nationalism. In so doing, the racial integration of American industrial and military forces were both part of the war effort and the war aims. The result was the inevitable abolition of legal segregation, something that had long been integral to the national federalization program of the New Deal Liberals.
The uneasy alliance between the Liberals and the Southern conservative Democrats - always the weakest link in the pluralist coalition of the New Deal realignment - shattered with the Dixiecrat revolt of the Southern Democrats in 1948. The revolt was the opening shot in the political struggle inside the establishment over civil rights. For the next twenty years, the turmoil over civil rights culminated in the abortive Goldwater campaign in the 1964 presidential elections. The significant feature of the Goldwater campaign was that it was conducted by insurgents on the right wing of the Republican Party. A significant feature of the Goldwater campaign was that it was the first Republican presidential campaign since before the Civil War to reach out into the Southern states. George Wallace recognized this fissure and capitalized on it during the 1968 presidential elections, peeling off a sector of reactionary white middle class (and largely union labor) from the Democratic Party.
Simultaneous fissures in the Democratic Party over the war in Vietnam further sundered the coalition formed during the New Deal. One thing to bear in mind about the protests against the Vietnam war is the protesters were largely young people who had been politicized by the Civil Rights movement. The civil rights and antiwar movements were a new force for social progressives. The social progressives eventually emerged as the current Progressive wing of the Democratic Party. In this context, the New Deal Liberals (now morphed into the Centrists) are the conservative wing of the Democrats and the Progressives are the liberals. Despite conservatives continual name-calling about "Liberals" (which is really just a code word for anybody they disagree with) the Democratic Party is divided between Centrists and Progressives. The significant feature of the Progressive revolt in the Democratic Party is that in a two party system, they have nowhere to go except the Democrats.
Following the 1972 presidential elections, there was an abortive split from the Democratic Party by Southern Conservatives. The exodus begun in 1948 by the Dixiecrats nearly happened in 1974, when a sizable number of Southern Democrats proposed to cross the aisle as a bloc and join the Republican Party. The Watergate scandal put these plans on hold for twelve years.
By 1980, the Democratic alliance created during the New Deal realignment had splintered for good. The driving force at the grass roots was a new style of polarizing, divisive and reactionary politics based on "wedge issues." The wedges were being used to break apart the New Deal Liberal coalition. The salient wedge issues were opposition to school integration, prayer in schools, abortion, the "war on drugs" and "law and order." Later additions to this style of politics include opposition to gun control laws, "property rights," immigration and homophobia. All of these issues strike directly at personal and social values. They are black and white, good and evil, right and wrong, win or lose. There is no compromise, no negotiation, no opportunity for resolution through any type of political solution or consensual process. They are, in the word of Chip Berlet, toxic to democracy.
But wedge issues did their job and a significant new plurality emerged in American politics in the mid-1970s, the Christian Right. Organized mostly around the wedge issues of abortion and school prayer, the Christian Right (initially in the guise of Jerry Falwell's Moral Majority) emerged as a factor in the 1976 presidential election. Because of the obvious weaknesses of Nixon's appointee, Gerald Ford, the Christian Right was not able to play a decisive role in the 1976 presidential elections, but they were clearly organizing as an emerging political and social force on the right.
The other group targeted by wedge issues became known as "Reagan Democrats." These were mostly white, mostly blue collar, mostly organized labor. In the 1972 presidential elections, Nixon had courted and won the support of George Meany and the AFL-CIO. This began the process of breaking up organized labor as a social and political force.
The 1980 election brought all of these forces into play and resulted in the resounding victory of Ronald Reagan over the Democratic incumbent, Jimmy Carter. Probably too much has been made of the missteps and misfortunes of the Carter administration as prologue to the Regan Revolution. The seeds of the conservative ascendancy were cast in the 1964 elections and bore first fruit in the next election with the ascension of Richard Nixon to the presidency. The last Democratic presidential candidate with clear affiliation with New Deal liberalism was George McGovern in 1972 and his resounding defeat was the death knell for the last vestige of the preceding realignment.
To sum up, the significant feature of every political realignment in American politics is the splintering of a ruling coalition with a sizable enough migration of voters and politicians from one party to another. As can be seen by the preceding history, the dynamics of the splits can be very different. They can arise because of a lop-sided majority inside of one party forcing out a faction, as happened to the progressive Republicans in 1912 and the expulsion of the progressive wing of the Democratic party in 1968. It can also happen by one party systematically breaking off and absorbing part of the base of their opponents, as happened with the conservative ascendancy in the 1980s. Whatever the cause of the split, it weakens the divided party. In some cases, like the trashing of the progressives by the Democrats, the minority faction can ultimately gain strength and reshape the party by rejoining it. This is particularly true when the splinter group moves away from the opposing party, as the progressive Democrats and ultra-conservative Republicans have done. The balance of power shifts by the migration from one party to another, thus forming a new ruling majority.
I'll break off here, since this has been a very long piece. In the future, I'll be applying the lessons of history to the current situation in both national and local politics.
Richard Hoffstader, "The Age of Reform"
Eric F. Goldman, "Rendezvous with Destiny: A History of Modern American Reform"
Rick Perlstein, "Before The Storm: Barry Goldwater and the Unmaking of the American Consensus"
Walter Karp, "Indispensable Enemies: The Politics of Misrule in America"
Godfrey Hodgson, "The World Turned Right Side Up: A History of the Conservative Ascendancy in America."