Actors Equity is the labor union for actors and stage managers in the United States. Founded in 1913 it is dedicated to fostering live theater in the U.S. The website is here. The Catch-22 with Actor's Equity is that you can't get a job without the union card and you can't get a union card without a job. There are ways around this. Often actors can gain Equity points from appearing in some productions in regional theaters. See also Equity for Great Britain