Democrats picked up three Republican seats, while Republicans took one held by a Democrat. All three states will figure prominently in the presidential map in two years.
The hotly contested race in Georgia, where Democrat Stacey Abrams was seeking to become the first black woman to be elected governor of a USA state, remained too close to call early on Wednesday.
In Michigan, Democrat Gretchen Whitmer defeated Republican Bill Schuette, upending years of Republican control in the state. Democrats did win gubernatorial races in Kansas, Wisconsin and IL, as well as four other states.
Republican Gov. Bruce Rauner in IL lost his bid for a second term to Democrat J.B. Pritzker. Pritzker, a billionaire, appears to have capitalized not only on Rauner's lack of popularity but broader dissatisfaction with President Donald Trump. Laura Kelly has been elected the state's next governor, CNN projects, defeating Republican Secretary of State Kris Kobach.
While Rauner lost his bid for another term, voters opted to return other incumbent governors, including Democrats Andrew Cuomo in NY and Tom Wolf in Pennsylvania, and Republican Charlie Baker in MA.
Republicans won single-party control in Alaska; Democratic victories in legislative and gubernatorial races restored two-party governance in New Hampshire, Wisconsin, Michigan and Kansas. Wisconsin Gov. Scott Walker, a former Republican presidential candidate and Trump ally, was seeking a third term in a race that remained too close to call.
Tuesday's elections feature contests for 36 governors' offices, including headliner races in Florida and Georgia.
Republicans are in control more often than not in state capitols across the country, but Democrats were trying to pull a little closer in elections Tuesday for governor and state legislature. Republicans were largely on defense but also were angling for gains in a few traditionally Democratic states, such CT.
State legislative results were similarly mixed (as were congressional outcomes).
Voters also were deciding ballot measures in four states - Colorado, Michigan, Missouri and Utah - that propose to overhaul the redistricting process and reduce the likelihood of partisan gerrymandering by either major party. That includes 25 states where they hold a trifecta of power, compared with just eight for Democrats. Democrats now have complete control of state government in Colorado, New York, Illinois, Maine and New Mexico.
Critical contests are taking place in Midwestern and Rust Belt states that sealed Trump's 2016 victory, where Republican losses could hurt his re-election chances in 2020.
The Democratic Legislative Campaign Committee and Republican State Leadership Committee, which focus on state races, also set record fundraising targets.
The governor's races have extra emphasis in 28 states where the winners will serve four-year terms with the potential power to approve or reject district boundaries drawn for Congress or state legislatures.
The Democratic Party said it flipped at least six state legislative chambers on the strength of local races. And it will nearly certainly influence how states redraw congressional districts after the 2020 census.