If you grew up in Pittsburgh in the 1950s, which I did, and if four of your uncles worked in steel mills, which four of my uncles did, you not only supported labor unions, you thought unions had helped create America's large, comfortable middle class of skilled laborers.
And that positive feeling about unions was widespread in 1955, when 75% of the public approved of labor unions and about 35% of all American workers belonged to a union, up from around 5% during the first years of the Great Depression of the 1930s.
The start of the American labor movement coincided with the start of the industrial revolution in the mid-19th century, and subsequently two men in particular acted as catalysts to its growth. Samuel Gompers founded the American Federation of Labor in 1886, the first national union that advocated on workers' behalf for better wages and benefits, improved workplace conditions and job security. But unions only gained ground slowly until Franklin Delano Roosevelt's New Deal policies in the 1930s lead to passage of the Wagner Act, which protected the rights of unions to organize workers. Union membership soared.
If union power then peaked in the 1950s, it began to decline in the 1970s. American manufacturing growth stalled, (Did you know that no steel is produced in Pittsburgh proper today!), historically non-union service industries and knowledge industries drove most employment growth, Federal legislation became much less union friendly, and the public attitude about unions began to shift.
Today, fewer than half of Americans approve of unions , including only 26% of Republicans, and only 11% of all American workers belong to a union, down from that 35% peak in 1955. And the mix of union members is skewed heavily to public sector jobs: to wit, 36% of public employees (e.g., teachers, postal workers) belong to a union, while only 7% of private employees are union members. All told there are now 14.5 million union members, down from a peak of 21 million in 1979. And that precipitous decline is even steeper when you take into account the fact that today's total workforce is much larger than it was almost 40 years ago.
But the effect of unions can't and shouldn't be underestimated. They triggered the Federal government to create the Bureau of Labor in part to safeguard workers' rights, and they drove private employers in non-union businesses to recognize that decent wages and better benefits and improved working conditions attract better, happier and more productive employees. In addition, labor unions were a driving force behind the creation of Labor Day.