The share of American workers in unions fell once again in 2018, from 10.7% in 2017 to 10.5%. The decline is part of a much longer-term trend of the slow and steady disintegration of organized labor in the United States. In 1983, according to the Bureau of Labor Statistics, 20.1% of American workers were union members.

Labor unions exist to increase the collective bargaining power of their members to negotiate higher wages and better benefits. And historically, they have done just that. According to the Bureau of Labor Statistics, the typical non-union worker earns just under 80% of the wages of the typical unionized worker on a weekly basis. Labor unions have also helped to greatly improve benefits and reduce pay inequality along lines of race and gender.

Based on figures published by Unionstats.com, an online union membership and coverage database, 24/7 Wall St. identified the states with the highest and lowest union membership as a percentage of total employment. The database, which analyzes Bureau of Labor Statistics’ Current Population Survey, provides labor force and union membership figures in both the public and private sectors. Annual average wages by state came from Bureau of Economic Analysis. Rates of change in union membership were calculated over the period of 2008 to 2018.

Labor unions are an inherently political issue, and some states are more likely to be receptive to collective bargaining than others. 24/7 Wall St. reviewed data from the Bureau of Labor Statistics to identify the states where union membership is the strongest and the weakest.

The public sector is much more heavily unionized than the private sector — 33.9% of public-sector workers are union members compared to 6.4% of those in the private sector. For this reason, states where government employment represents a larger share of total workers tend to have stronger overall union representation.

While unions provide benefits to workers, anti-union advocates argue that unions stifle economic growth, limit corporate competitiveness, and unfairly pass higher costs down to the consumer or taxpayer. They argue that states that have passed right-to-work legislation — laws that prohibit unions from requiring workers in certain trades to be due-paying members — are better states for business. As of today, the majority of states have passed right-to-work laws. Here is our ranking of all 50 states based on how favorable their business climates are.

Click here to see the states with the strongest and weakest unions.