The passage of so-called right-to-work legislation in Michigan fails to take into consideration the real impact unions have on both states’ and the nation’s economies and on middle-class Americans. “Right-to-work” laws weaken unions by making them provide services to union and nonunion members alike, without making all beneficiaries pay their fair share. By severely weakening unions, which are vital to strengthening the middle class and improving the economy, “right-to-work” laws have broad negative consequences.

Here are the key facts you need to know about unions’ value for the economy and the middle class.

1. Unionization increases income—not just for union workers but also for the entire middle class. A study conducted by the Center for American Progress Action Fund controlled for a host of other factors that also impact the strength of a state’s middle class—such as education, unemployment, and types of industries—and found that if unionization rates increased by 10 percentage points, the typical middle-class household, unionized or not, would earn $1,501 more each year. To put that figure in perspective, we found that a 10 percentage-point increase in the share of the population with a college degree would increase the average middle-class income by $1,664 a year.

2. In non-“right-to-work” states, workers are more likely to receive employer-provided health insurance and pensions. Workers in “right-to-work” states are significantly less likely to receive employer-provided health insurance and pensions. If benefits coverage in non-“right-to-work” states were lowered to the levels of states with these laws, 2 million fewer workers would receive health insurance and 3.8 million fewer workers would receive pensions nationwide.

3. Unions improve workplace policies and have beneficial policy effects more broadly. Unions advocate for broader worker protections needed for families to make human-capital investments—strong public education, social safety nets, minimum wages, paid leave, and even civil rights and efficient regulation.

4. Unions balance structures of power in the workplace, resulting in greater efficiency. Unions support high-productivity workplaces where information can flow from the bottom-up to improve business performance.

5. “Right-to-work” legislation fails to grow state economies. The laws have failed to increase employment growth in the 23 states that have adopted them, and in states more recently adopting “right-to-work” policies, employment growth and business relocations have reversed their previous expanding trends. In other words, the economic evidence shows that unions and union membership—not “right-to-work” laws—are what are conducive to broad economic growth.

6. Unions strengthen businesses and the economically vital middle class by giving workers a voice in both the workplace and our democracy. Unions do this by pushing for fair wages and good benefits, and also by encouraging citizens to advocate for middle-class-friendly policies such as a strong Social Security system and family-leave benefits.

Katie Murphy is an intern with the Press team at the Center for American Progress.