Answer: Trade unions are organizations that represent the interests of workers.
Explanation:
Trade unions are an integral part of many industries and corporations around the world. Their task is to represent the interests of the workers. In the United States, the existence of a trade union was established by law in 1935. The unions negotiate with employers about wages, working conditions, benefits and work organization. The strongest unions in the world today are parts of the public sector, such as the police, teachers, civil servants and the like.
I believe they were called unionists as they were part of the Union. The south was the Confederacy therefore southerners were Confederates.