CHICAGO — Come January, more than two-thirds of the states will be under single-party control, raising the prospect that bold partisan agendas — on both ends of the political spectrum — will flourish over the next couple of years.

Though the Nov. 6 election maintained divided government in Washington, the picture is starkly different in capitals from California to Florida: one party will hold the governor's office and majorities in both legislative chambers in at least 37 states, the largest number in 60 years and a significant jump from even two years ago.