Final answer:
The question refers to U.S. segregation laws where African Americans were required to give up bus seats for white passengers. Such laws were part of the broader Jim Crow system of racial segregation, which was later deemed unconstitutional, partially due to civil rights activists' efforts.
Step-by-step explanation:
The question touches on a historical context rather than current transportation regulations. It refers to a period in the United States history when buses could carry both passengers and their belongings, including baggage and freight. However, the critical part of the question seems to pertain to racial segregation laws, particularly those that were in place in the United States before the civil rights movement. During this time, if a bus was crowded and a white passenger had nowhere to sit, African Americans were required by law to give up their seat. This law was one of the many examples of legal segregation under the Jim Crow laws, which enforced a system of racial segregation and disenfranchisement.
It is important to note that these practices were eventually challenged and found to be unconstitutional, partially due to the efforts of civil rights activists. The most famous act of defiance against this policy was by Rosa Parks in 1955, when she refused to give up her seat to a white passenger, an event that became one of the catalysts for the civil rights movement.