Question

What did workers do when they signed yellow-dog contracts

Answer 1

A yellow dog contract is an employment contract that includes a commitment by the worker not to be a member of a labor union.  These contracts were extended in the United States until the 1930s to prevent the formation of trade unions. In 1932, yellow dog contracts were abolished in the United States by the Norris-LaGuardia Act.

Answer 2

an agreement signed by a worker promising not to join a union while working for a company.