Ballotpedia:Who Runs the States, Partisanship Results, Partisan Control of State Senates
The two major political parties claim that their policies will lead to better outcomes. What does the data show?
At Ballotpedia, we explored these issues in a three-part study, Who Runs the States.
This page contains the section of the report pertaining to the Partisan Control of State Senates.
Partisan Control of State Senates
Over the 22-year period of the study, Democrats held a greater share of the 49 partisan state senates than the Republicans. The Democrats controlled the state senates 50.2 percent of the time, while Republicans held the upper chambers 48 percent of the time. Senates were tied without a lieutenant governor’s vote as a tie breaker or run by power-sharing agreements between the two parties less than 2 percent of the time. On average, state senates were controlled by Democrats for 11 years and by Republicans for 10.6 years. The Democrats controlled 23 senates for more years than the Republicans did, and the Republicans had majorities more often in 22 states. Among these, Democrats and Republicans controlled 16 and 13 state senates, respectively, for than 80 percent of the time. In four state senates, the Democrats and Republicans held control for the same number of years.
More state senates have come under Republican control in recent years. During the first 11 years (1992-2002), Democrats held state senate majorities 283 of 539 possible times (52.5 percent), with each year in control of a state senate counting as one time. The Republicans held state senate majorities 245 times (45.5 percent). However, in the second half of the study (2003-2013), the GOP took the lead, controlling state senates 272 times (50.5 percent). The Democrats held senate majorities 258 times (47.9 percent). In 1992, the Democrats controlled their greatest number of state senates (34), and the Republicans held majorities in only 14 senates, their lowest during the 22-year period. In 2013, the Republicans control 31 state senates, their highest, while the Democrats hold majorities in 18 senates, their lowest.
Most state senates were under control by the same party for more than 80 percent of the years studied. The Democratic Party and the Republican Party ran 16 and 13 state senates, respectively, for more than 80 percent of the time. From 1992 to 2002, the Democrats were in charge of 20 senates more than 80 percent of the time, while the Republicans held 16. However, during the past 11 years, the GOP was in the majority more than 80 percent of the time in 18 states. In that same time, the Democratic Party was in the majority more than 80 percent of the time in 17 states. So, over the past 11 years, 35 state senates saw one party in power more than 80 percent of the time, 1 fewer than the number of states with this situation in the first 11 years.
Only 15 state senates were run by one party for all 22 years. The Democrats were in charge of eight state senates for the entire period. Seven state senates were exclusively controlled by the Republicans. The other 34 partisan state senates had at least one year of control by each major party.