Final answer:
The buses started their journey in Washington, DC, on May 4, 1961, as part of the civil rights-era Freedom Rides.
Step-by-step explanation:
The buses referred to in the question are those used during the 1961 Freedom Rides. These rides were crucial events during the Civil Rights Movement where African American and White volunteers challenged segregation laws in the American South.
Departing from Washington, DC, on May 4, 1961, the Freedom Riders embarked on their journey, with the goal of enforcing a U.S. Supreme Court decision that prohibited segregation in interstate transportation.
The Freedom Riders aimed to challenge and protest against segregated waiting rooms in southern bus terminals as they traveled through Southern states such as South Carolina, Georgia, and Alabama.