Hostess Brands, the maker of Twinkies, Ding Dongs and Wonder Bread, said it would liquidate and layoff 18,500 workers after workers went on strike protesting pay cuts.
Only 11% of manufacturing workers were union members in 2011, down significantly from 24% in 1986.
Two thirds of those people work in durable goods manufacturing, making products like automobiles, appliances and machinery.
The other third make nondurable goods like food, textiles, paper products and chemicals. These include Hostess workers, who went on strike in early November and then lost their jobs when the company folded.
In manufacturing, union workers make about $836 a week, $56 a week more than non-union employees.
Major unions: United Automobile, Aerospace and Agricultural Implement Workers of America; International Association of Machinists and Aerospace Workers; International Union of Operating Engineers