Polarization and state legislative elections

US state legislatures are critical policymaking institutions that are increasingly polarized, yet data and measurement limitations have prevented researchers from understanding how state legislative elections contribute to this polarization. To address this gap, we construct new measures of candidate ideology based on campaign contributions and roll-call votes, and we use them to offer the first systematic study of the relationship between candidate ideology and electoral outcomes in primary and general elections in state legislatures, 2000–2022. We find that the set of people running for state legislature has polarized substantially in recent decades. More-moderate candidates enjoy a meaningful advantage in contested general elections, but that advantage has declined somewhat in recent years. At the same time, more-extreme candidates are favored in contested primary elections. These new measures and data will allow researchers to build on these basic findings to understand how elections function in lower information, lower salience environments like American state legislatures.