In the 19th century and continuing well into the 20th, the United States saw a proliferation of political parties, many operating within a single state or region, and often achieving a substantial degree of electoral success. The most successful of these coalesced to form what is now the Republican Party.
This competitive market for political organizations produced the creative destruction of the Whigs and put a new, much better anti-slavery party in control of the White House and Congress. But we haven’t seen the emergence of a new major party since then, and few serious attempts. Instead, alternative parties are relegated to the irrelevant fringes.
So what changed? The single greatest cause for the decline of this marketplace of ideas was the prohibition of fusion, also known as cross-nomination.
Fusion is simply the ability of multiple parties to nominate the same candidate if and when they want. For example, both Republicans and Libertarians might want to back the same candidate in some races, or likewise the Democrats and the Working Families Party. On rare occasions an exceptionally popular candidate might even appeal to primary voters in both major parties.
In banning fusion, mostly at the height of the Progressive era, unjustified government control was asserted over core political speech and freedom of association. The consequences of this change have been widely overlooked, but go to the core of why our political system is so toxic and dysfunctional today.