The Great Depression. How could a union survive this?

The stock market crash of October 1929 would leave the USA with an unemployment rate of 25%.

Besides lost union members, the members that remained fell on hard times trying to support more family than they had before and could not afford to pay their union dues.

Oddly enough, the unions did not rally behind the extremist that was over taking the populous movements.  They stood by until 1932 when "The Norris - La Guardia Anti-Injunction Act was passed.

President Herbert Hoover recognized the need for unions to protect workers more than ever and passed stringent laws against injunction laws during labor disputes.  These new laws would apply to the federal courts, but, many states would follow.  It gave a reassurance to the labor movement which gained the confidence of the American public and a nod from government to protect its laborers.