The Vanishing Incumbency Advantage in State House Elections

Ninety-six percent of state legislative incumbents who appeared on the November 2022 ballot reclaimed their seats in the state legislature, the highest percentage since at least the 2010 elections. Such electoral success would suggest that these state legislators enjoyed a healthy incumbency advantage. However, prior work (e.g. Jacobson, G. C. 2015. "It's Nothing Personal: The Decline of the Incumbency Advantage in US House Elections." The Journal of Politics 77 (3): 861-73.) indicates that the incumbency advantage has diminished in recent elections, at least in the US House. I find similar - but smaller - declines in the magnitude of the incumbency advantage in state house elections in the last two decades. Instead of being attributable to the traditional incumbency advantage, state legislative incumbents' success in the 2022 elections is more likely a consequence of the increasing number of partisan state house districts and the continued nationalization of state politics.