Data on the total number and the proportion of employees who are union members in the private and the public sector comes from the Bureau of Labor Statistics Current Population Survey 2018. The same source is used for data on median wages for union and non-union members, union membership in the private sector by industry, and union membership by age group. The analysis considers data from January to December 2018. The 10-year union membership growth variable is calculated as the difference between the proportion of union membership in 2018 and 2008 for every state.
Data on unemployment is from the Bureau of Labor Statistics 2018 Local Area Unemployment Statistics Survey. Median income per state is from the U.S. Bureau of Labor Statistics 2018 Occupational Employment Statistics Survey. Information about inequality is from the U.S. Census Bureau 2017 American Community Survey 1-Year Estimates.
For a complete list of results for all states, see the original version on Construction Coverage.