We use a simple average of median household income within the high-, medium-, and low-union-density state groupings. Union density is defined as the share of workers in the state who are represented by a union, including union members and other workers who are covered by a union contract, based on the variable “union” from EPI extracts of CPS-ORG microdata. We average union density data across 2022 to 2024 for each state to give a more accurate estimate of states’ typical unionization rates over time. Low-union-density states are the 17 states with the lowest average union densities (with union densities ranging from 3.0% to 8.1%). Medium-union-density states are the 17 states (including D.C.) in the middle of the union density rankings (with union densities ranging from 8.2% to 13.1%). High-union-density states are the 17 states with the highest average union densities (13.4%–25.5%). See Table 1 for more detail about these groupings.