June A. McCarroll was born in Elkhorn, Wisconsin. Her early life and upbringing remain relatively obscure, but her later achievements suggest a strong character and dedication to service, perhaps instilled during her formative years in the Midwest.

June McCarroll established herself as a physician. While specific details of her medical practice are not extensively documented, her profession likely instilled in her a strong sense of public health and a commitment to preventing injury and saving lives. This commitment would later translate to her advocacy for road safety improvements.

While driving along a narrow stretch of road near Indio, California, McCarroll was forced off the road by an oncoming truck. She later claimed this incident sparked the idea of painting a line down the center of the road to separate traffic and prevent similar accidents. This experience appears to be a pivotal moment that directed her energies toward advocating for road safety.

Following her near-accident, McCarroll embarked on a relentless campaign to persuade local authorities to adopt her idea of painted highway lines. She personally painted a white line down the center of a particularly dangerous stretch of road near Indio. She began by convincing the local chamber of commerce, gaining support from prominent community leaders.

McCarroll's persistent advocacy paid off as the California State Highway Commission officially adopted the use of painted lines to delineate lanes on state highways. This marked a significant turning point, establishing the painted line as a standard safety feature throughout the state.

McCarroll remained an active advocate for road safety, promoting initiatives to improve driver awareness and reduce accidents. Although her most significant achievement was behind her, she continued working tirelessly to improve road conditions and safety standards for everyone.

June McCarroll passed away in Indio, California. While the extent of her sole influence is disputed, she is remembered for her passionate advocacy and role in promoting the adoption of a safety measure that undoubtedly saved countless lives. She left a legacy of improved safety standards and a testament to the power of individual initiative.