About 12% of U.S. workers were union members last year. Here are 8 of the most heavily unionized jobs.
About 1.1 million protective services workers -- cops, firefighters, corrections officers and security guards -- are union members, accounting for 35% of the entire occupation.
For these workers, the pay gap can be huge between a non-union and union job.
Union workers make about $1,008 a week, and non-union workers make $627, according to the Bureau of Labor Statistics.
Major unions: International Union of Police Associations; International Association of Fire Fighters
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