(With thanks to Wikipedia): The Red Ball Express was a famed truck convoy system that supplied Allied forces moving quickly through Europe after breaking out from the D-Day beaches in Normandy in 1944. In order to expedite cargo to the front, trucks emblazoned with red balls followed a similarly marked route that had been closed to civilian traffic. These trucks were also given priority on regular roads.
The system originated in an urgent 36-hour meeting and began operating on August 25, 1944, staffed primarily with African-American soldiers. At its peak, the Express operated 5,958 vehicles, and carried about 12,500 tons of supplies a day. It ran for 83 days until November 16, when the port facilities at Antwerp, Belgium, were opened, enough French rail lines were repaired, and portable gasoline pipelines were deployed.