A total of 723 state legislative special elections took place from 2010 to 2019 in 31 states. The following states held the most special elections during that time period:

• Georgia: 63
• Pennsylvania: 43
• New York: 42
• Louisiana: 40
• Massachusetts: 40
• Connecticut: 37
• Mississippi: 36
• Virginia: 34
• Texas: 32
• California: 31
• South Carolina: 31

The largest number of special elections in a given year were held in 2018 with 99 special elections. There were just 30 special elections held in 2010. Georgia held the most special elections in a single year with 12 special elections in 2015. New York and Georgia held 11 special elections in 2018 and 2011, respectively.

Ninety-seven state legislative seats changed partisan control in special elections from 2010 to 2019. Democrats flipped 52 seats, Republicans flipped 39 seats, and independent and third-party candidates flipped six seats. Seventeen seats flipped in 2017, the highest number in any year since 2010. The state with the most flipped seats is New Hampshire with 10 seats changing partisan control. An additional seat flipped in New Hampshire as a result of a special election in March 2020. Four states (Connecticut, Massachusetts, New York, and Oklahoma) are tied for second with seven flipped seats each.

So far this year, 43 state legislative special elections have been scheduled in 20 states. Special elections have been held for 22 seats so far; heading into those races, Democrats had previously controlled 10 of the seats, while Republicans previously controlled 12. One seat has flipped from Democratic control to Republican control. One seat has flipped from Republican control to Democratic control.