So what's behind this potentially record-breaking instability? There are four broad reasons that explain the upheaval:
2014 could mark an ideological course correction for some states after the big GOP wave of 2010.
The Republican wave of 2010 pushed a handful of GOP governors to victory in blue states won twice by President Obama, including Florida, Maine, Michigan, Pennsylvania, and Wisconsin. Two governors in particular, Maine Gov. Paul LePage and Florida Gov. Rick Scott, won by exceedingly close margins. Democratic wins in any of these states wouldn't so much be a coup as a course correction after a simply brutal showing for the party in 2010.
One big consequence of Tuesday's elections could also be the return of divided government, and not just in Washington. Since 2010, Congress has been mired in gridlock, but state legislatures have not. Thirty-six states, a historic number, are currently under single-party control, and unlike in Washington, that's given legislators the flexibility to pursue policy agendas that have proven controversial at times, particularly in purple states where voters tend to be unforgiving of veers too far to the left or right.
From Democrats' package of new gun laws in Colorado and their troubled implementation of Obamacare in Maryland to Republicans' moves to curtail union powers in Michigan and Wisconsin and make education cuts in Pennsylvania, governors across the country have gotten a lot done with little input from the other party in the last few years, sparking close reelection races for many of them.
Local issues are separating races from the national environment.
Whether it's a National Guard scandal in Alaska or general dissatisfaction with state government in Hawaii, even deep-red or blue states aren't immune from this year's gubernatorial instability. Some of the biggest issues in the purple states have been local ones, too, from the fate of a convicted murderer on death row in Colorado or the rigid polarization over Wisconsin's state budgets and Gov. Scott Walker (the only potential 2016 presidential candidate who's in danger of losing Tuesday), each state has its own story to tell, and those stories will shape the outcome of many races.
This is particularly evident in contests that threaten to buck the traditional partisan lean of their state—like Massachusetts or Kansas. In the latter, a fraying local GOP coalition could spell the end of Gov. Sam Brownback's tenure despite the friendly nationwide environment for Republicans, while in Massachusetts, Democrats are relearning, after eight years under Gov. Deval Patrick, that nothing is automatic even in a state that tilts heavily Democratic in national elections.
The state of the economy is still up for debate.
The economy has been central in state-level contests, but the impact has been uneven. The economy has improved in every state since 2010, but voters not feeling those positive jobs numbers—whether due to continued unemployment or wage stagnation—could still vote out governors who took office four years ago.