Kind of like when you are on a group ride where people are maintaining 2 abreast and someone decides to pass and crosses the yellow line and into potential oncoming traffic.
The race route was on US23 for about 5 miles heading North out of Delaware State Park. It is a 4 lane divided highway with a frontage road for a stretch. The shoulder looks decent. I wonder if they marked off one lane or planned for everyone to ride on the shoulder.
20/20 hindsight but that is a darned busy looking road.