Americans are fond of diversity in the private market. We like a broad array of choices in ice cream, in radio stations, in ethnic food, and in automobiles. We also celebrate diversity in the political marketplace. Perhaps then it ought to surprise you that there are but two major national political parties that have any realistic chance to win either the presidency or the majority of seats in the two houses of the national Congress. The same is true within states for governors and state legislative seats. We have a thorough political duopoly of Republicans, Democrats, or nothing. My job is to explain why.
We know exactly why some democratic polity or state will tend to have two parties, and others have more than that. The answer is structural; it's the rules used to convert popular votes into electoral seats in power. Countries with more than two parties holding seats in their national assembly usually employ proportional representation (PR). The principle is simple: if party A harvests 20 percent of the vote, it will receive a proportional 20 percent of the seats. The U.S. does not use PR; it uses "first past the post" or single-member, simple plurality (SMSP). This principle is also simple: if you and your party win the most recorded votes in a given election, you win that post. The 50 state governorships, 100 U.S. Senate seats, 435 U.S. House seats, and 51 units with their 538 presidential Electoral College votes are all decided on this basis. For further simplicity it's called winner-take-all; but I employ SMSP to denote that most (not quite all) American elections require only a plurality rather than an outright majority to win all.
SMSP is a profound disincentive to third parties. These arise and contest elections; they often act as spoilers causing an established party's candidate to lose; they introduce new issues and arguments into campaigns; they boost voter turnout by offering an interesting third way. But it asks too much for one to arise from the grassroots and actually win. What happens if a third party should arise across a nation and fare well enough to capture 20 percent of the voters' allegiance? In PR countries, that's likely to put them in business with approximately 20 percent of the seats in a House of Commons or its like. In SMSP countries, they're likely to lose everywhere. You can see this quite readily via Dave Leip's Atlas of U.S. Presidential Elections illustration for 1992, when Ross Perot's lavishly funded third party presidential bid harvested 18.9% of the national popular vote but did not win any of the 50 states plus D.C. with their 538 Electoral College votes (1992 Presidential Election Results). This isn't a new story. In 1912 Theodore Roosevelt was spurned in seeking to oust incumbent Republican William Howard Taft from the Republican presidential nomination; so he turned to a Progressive or "Bull Moose" third party and actually outpolled Taft nationally in popular vote and Electoral College. But with the once-majority Republicans cleaved like this, the smaller party Democrats' Woodrow Wilson easily won vote pluralities in state after state to cruise to a decisive 435 to 88 Electoral College victory (1912 Presidential Election Results). T.R. had had enough after that; in 1916 he retired from this enterprise and returned to the GOP. This time they ran one candidate, Charles Evan Hughes, and almost defeated Wilson despite the latter having a spectacularly successful first term as president (1916 Presidential Election Results). Later, in 1924, the Progressive Party tried again, with their champion Robert LaFollette of Wisconsin, but his 16.6% of the nation's vote won only his home state of Wisconsin with 13 votes (1924 Presidential Election Results). The 1928 election saw no repeat of this. But 20 years later in 1948, southern defenders of segregation were angry enough with the Democratic Party's endorsement of integration to run Strom Thurmond on a third party. It worked to win four of the deepest southern segregationist states but failed to deny general election victory to Democrat Harry S. Truman (1948 Presidential Election Results); in 1952, the Democrats heeded the warning and avoided talking about integration during that campaign. Another 20 years after 1948, southern segregationist George Wallace of Alabama went third-party and helped defeat the national Democrat; but the Republican, not Wallace, won the election (1968 Presidential Election Results). And in 1972 when he was shot and nearly killed during his springtime presidential campaign, Wallace was contested the Democratic Party's Maryland primary election. He had abandoned his own party after it served his onetime purpose. Now Ross Perot in 1996 was different; he'd won 18.9% in 1992 and had visions of grandeur and success four years later. But despite keeping its candidate and its funds aboard, this third party did not encourage voters to believe it had a chance. So in 1996 its vote harvest declined by more than half to just 8.40% (1996 Presidential Election Results).
That's the SMSP story. One eventually has to conclude that American third parties matter a lot, but they do not win and do not survive to hold seats in power. The electoral game is rigged for just two players to stay in business. American separation of powers contributes a great deal to this. Look at the dominance of the two parties in holding 20th century congressional seats (Renka, Presidents and Congresses). The "other" category for third party seats is virtually empty. It's a lot to ask a third party not only to run a national presidential campaign, but also to produce a viable slate of congressional candidates in 50 states and hundreds of congressional districts.
But if you are a sharp-eyed watcher of regionally based presidential elections, you'll quickly notice that parties have often enjoyed a concentrated power base. This is evident here: Presidential Election Maps, by County. The 1968 Wallace campaign did win 4 southern states and a great many counties (colored in green). Surely they might have won the senatorial and congressional seats from there, too. The general point is that even use of national SMSP elections won't protect against a regionally dominant third party. Our northern neighbor of Canada in fact demonstrates this quite nicely, as it has the large French-speaking province of Quebec housing the semi-separatist Bloc Québécois party. It fares well in French locales and poorly to nonexistent elsewhere. We see the result in the 2006 Elections Canada - National (with provincial map at The Atlas of Canada - The 39th Federal Election, 2006). Canada's (or more accurately, Quebec's) French party has a share of parliamentary seats, a stake in power, and no reason whatsoever to fade out of existence after an election. This pattern crosses elections rather than being strictly temporary. The 2006 result is essentially similar to 2004, per The Atlas of Canada - The 38th Federal Election, 2004, and earlier (The 37th Federal Election, 2000).
But in America, everything in the blitz of detail about six successive historical party systems does not override one fundamental fact: the two American parties are organized to exist in all states, to participate in presidential nominations, and to contest for the presidency. Both parties are truly national. There is no American parliament to negotiate the choice of a Canada-styled Prime Minister out of some coalition among two or three parties; there is only the nationwide Electoral College with electors obediently casting votes in deference to the state's popular vote plurality of November 2-8. Look back through Presidential Election Maps, by County for the many decades of southern dominance by Democrats before the 1950s-60s civil rights era. Why, one can ask, would a southern Republican Party even bother to exist in the 11 old confederacy states below the Mason-Dixon line? They obviously could not win elections in this one-party terrain filled with white voters who were taught from childhood about the evils of Republican-run occupation of the southland. Or one can also look at Utah and Idaho in very recent elections to ask whether it's worth having a Democratic Party there at all in such Republican-dominated locales.
The answer comes this way: Democrats in Idaho and Utah do exist, do participate in presidential primaries, do go to the convention to cast votes for the party's nominee. After that, surely the gig is up; but it's still worth having a party and showing the flag there. Besides, for ambitious political persons, these parties offer far fewer internal obstacles on the climb toward prominence than the state's dominant party does. Parties thrive only to the extent they work as vehicles for the ambitious to advance. During the long decades of Democratic dominance in the south, Democratic state parties were led by luminaries whose grip on power and highest office was virtually unbreakable. Imagine being a young George H.W. Bush in the 1940s, journeying to Texas to make your political fortunes, and discovering that within its state Democratic Party resided Senator Lyndon Johnson (aged 40 in 1948) AND Speaker of the House Sam Rayburn (known universally as "Mr. Sam")! The Texas GOP was moribund, but it did exist, did send delegates to presidential conventions, did contribute to national decisions affecting the presidency, and did offer some hope that if ever Texas turned away from one party, another was already on hand to provide an alternative. And that is precisely what happened in the long upward path for Daddy Bush in the 1960s, 1970s, and 1980s.
In other words, America not only discourages third parties via use of SMSP. It also discourages them through existence of decentralized, state-based parties that participate everywhere in choosing national presidential nominees. That's a double deterrent to any sustained existence of American third parties. A regional third party like George Wallace's American Independent Party of 1968 offers the chance to change racial politics in a conservative direction. But it cannot hope to actually win office, and its supporters forfeit the chance to participate within the emerging southern Republican parties. That's an historical wrong path for them. The white South nowadays has gone to the GOP, and the nonwhite south along with a handful of culturally liberal bastions (Austin, Athens, Raleigh) have gone to the Democrats. What other realistic choice do they have?
Russell Renka