Rosa Parks' refusal to give up her bus seat to a white passenger in 1954 triggered the renowned Montgomery bus boycott, but it was a less familiar protest action by Irene Morgan a decade earlier that led the U.S. Supreme Court to rule that segregation on interstate buses was unconstitutional. In the spring of 1946, Morgan climbed on a bus in Tidewater Virginia, bound for Baltimore. The driver ordered her to the back, but Morgan refused. She was arrested and fined $10. Thurgood Marshall argued the case at the Supreme Court, his fourth appearance there. Marshall argued:
Today we are just emerging from a war in which all of the people of the United States were united in a death struggle against the apostles of racism. How much clearer must it be today than it was in 1877, that the national business of interstate commerce is not to be disfigured by disruptive local practices bred of racial notions alien to our national ideals?
In the spring of 1946 the Supreme Court decided almost unanimously that state segregation placed an 'unfair burden' on interstate commerce, spelling the demise of legal segregation in interstate transportation.