How the American Two-Party System Became so Divided

“It would be a great tragedy if we had our two major political parties divide on what we would call a conservative-liberal line. [O]ne of the attributes of our political system has been that we have avoided generally violent swings … from one extreme to the other. And the reason we have avoided that is that in both parties there has been room for a broad spectrum of opinion.”—Vice President Richard M. Nixon, 1959

Since “the country was already split vertically between sections, races, and ethnic groups” it would be “dangerous to split it horizontally too between liberals and conservatives.” Down that path “lay the rift between haves and have-nots and the ideological politics of Europe.” —Attributed to Robert F. Kennedy, 1963

Those quotes are taken from , a new book about the U.S. party system. Rosenfeld studies those mid-century Americans, right and left, who rejected the opinion of Nixon and Kennedy—and helped form the highly ideological party system of today. I interviewed Rosenfeld by Google Doc on March 16. The conversation has been edited and revised for concision and clarity.