Union County er navnet på flere fylker i USA:
Union County (Arkansas) Union County (Florida) Union County (Georgia) Union County (Illinois) Union County (Indiana) Union County (Iowa) Union County (Kentucky) Union County (Mississippi) Union County (New Jersey) Union County (New Mexico) Union County (Nord-Carolina) Union County (Ohio) Union County (Oregon) Union County (Pennsylvania) Union County (Sør-Carolina) Union County (Sør-Dakota) Union County (Tennessee)
Union Parish i Louisiana