Republicans now will hold at least 32 governorships, including newly won offices in traditionally Democratic Illinois, Maryland and Massachusetts, says The Associated Press.
And the GOP will have full control of at least 29 state legislatures, according to the National Conference of State Legislatures. Democrats now control both chambers in 11 states.
The GOP's success is "a critical development at a time when most major policy has been coming out of states, rather than Washington," says The New York Times.
In recent years, Republicans have used their majorities to cut taxes, restrict abortions, expand gun rights and limit the powers of public employee unions.
"The challenge for Republicans may be to constrain their enthusiasm, lest they go further than some voters had anticipated and complicate their chances of re-election in the future," says AP.