U.S. Labor Unions

What do you gentlemen think of labor unions in the U.S.?
What, in your eyes, are the costs and/or benefits of having them?

Labor unions must exist to allow workers to negotiate as a singular entity. In the absence of unions the owners negotiate as a singular entity but the workers are all on their own. When you have a bunch of disparate voices arguing against one strong voice you don't have an equal footing.