We've already seen examples of this. The key event in Kansas politics this year was the defeat of moderate state senators by Republicans in the August primary. The November election was irrelevant.
This is reminiscent of the one-party politics in the Old South, in which victory in the Democratic primary was, according to the political cliche, "tantamount to victory."
Political junkies may want to dust off their copies of political scientist V.O. Key's classic "Southern Politics," first published in 1949, which showed how each Southern state had its own particular brand of one-party politics.
For the national public, one-party Democratic and one-party Republican states provide a look at how each party governs -- and the results.
In California, voters just gave Democrats two-thirds majorities in both houses and a tax increase, as well. We'll see if their policies help California reduce its dismally high unemployment and resolve its enormous pension underfunding.
In Illinois, Democrats won again, despite increasing the state income tax from 3 to 5 percent in 2011, after which the state's unemployment rate went up, while declining in neighboring states. Democrat Michael Madigan has been speaker of the Illinois House for 28 of the last 30 years.
Many Republican governors and legislatures have gone in another direction, holding down spending increases and seeking to cut taxes or hold rates even, rather than raise them.
Texas' low taxes (no income tax) and light regulation have been followed by some of the most robust job creation in the nation. Texas' population grew so rapidly in the last decade that it gained 4 U.S. House seats from the 2010 Census.
No-income-tax Florida gained two seats, and no other state gained more than one. California, for the first time in its history, gained none.
States are laboratories of democracy, Supreme Court Justice Louis Brandeis wrote. Citizens of every state can monitor their experiments and judge which set of one-party states is getting better results.