The Economic Policy Institute has produced a lengthy eye-popping report titled "How today’s unions help working people". It covers a lot of ground:

‘Collective bargaining’ is how working people gain a voice at work and the power to shape their working lives
Union workers are diverse, just like America
Unions represent workers of all levels of education
Union workers hail from a variety of sectors, but the biggest share work in education or health services
Unions are most widespread in public administration and transportation industries
Unions are thriving in diverse workplaces—including ‘new economy’ workplaces
Unions strengthen democracy by giving workers a voice in policy debates
Unions reduce inequality and are essential for low- and middle-wage workers’ ability to obtain a fair share of economic growth
Unions raise wages for both union and nonunion workers
Unions help raise wages for women and lessen racial wage gaps
Unions improve the health and safety practices of workplaces
Unions support strong families with better benefits and due process
Unions are good for workers’ retirement security
Unions create a path to sharing knowledge and solving problems
Workers still want unions but are being thwarted by aggressive campaigns and lobbying that have eroded private-sector union membership
Employers often fight unionizing efforts with aggression and intimidation, using legal and illegal tactics
Corporate lobbyists push laws—misleadingly called ‘right-to-work’ laws—that seek to defund private-sector unions
Corporate lobbies and allied lawmakers are dismantling the rights of public-sector union workers
Attacks on public-sector collective bargaining are playing out in the courts
Conclusion: Unions are essential to a fair economy and a vibrant democracy

But perhaps most striking was this graph

The best economic policies aimed at improving working and middle class standards, would be those that promote the growth and health of labor unions. Right now, we're going in the wrong direction.