The Michigan Department of Transportation claims to have painted the first centerline in 1911, predating McCarroll's incident in 1917. These claims are often cited in discussions about the origins of the highway centerline.

The Federal Highway Administration acknowledges the existence of earlier instances of painted centerlines but does not definitively attribute the idea to any single individual. They recognize the widespread adoption of the concept and its importance to modern highway safety.

Historians and transportation experts continue to research the origins of the painted centerline, examining archival records and anecdotal evidence to determine the most accurate account. The debate highlights the complexity of attributing inventions and the importance of considering multiple perspectives.

Despite the debate, June McCarroll remains a significant figure in the history of road safety. Her advocacy and efforts to promote the idea of the painted centerline contributed to its eventual widespread adoption, regardless of whether she was the absolute first to conceive of it.