This question, I assume, refers to the time in the 1920s, when African American porters on Pullman cars (sleeping cars on trains) tried to create a union. Their effort to unionize was led by a man named A. Philip Randolph. Working conditions were one of the issues that drove the porters’ desire to organize and form a union.
Sleeping car porters were all African American. The passengers who they served were almost all white. The black porters were treated very poorly by the Pullman Company. They were not paid much, as they were expected to make money on tips. They were not allowed to move up and become conductors. They had to pay if their passengers stole items from their compartments. They had to pay for their own food and uniforms. They had to spend a good deal of time working without pay to prepare the trains before trips and to clean them after. All of these things angered the porters greatly and made them want to organize.