The St. Lawrence Marathon, formerly known as the "Cornwall Run to End MS," is a scenic and community-focused race series along the shores of the St. Lawrence River in Cornwall, Ontario. This sold-out springtime tradition attracts runners of all levels, offering flat, fast courses through tranquil waterfront pathways and historical settings.

Participants can choose from distances including Marathon, Half Marathon, 10K, and 5K, each providing a chance to experience local camaraderie, Boston Marathon qualifying standards for the full marathon, and a friendly, welcoming atmosphere.

- Scenic waterfront courses along the St. Lawrence River
- Boston Marathon qualifier for the full marathon
- Certified course by Athletics Canada
- Flat, mostly asphalt paths with slight net downhill
- Community event with friendly atmosphere and local pride
- Age-based discounts and free entry for seniors 80+
- Sold-out, well-organized spring racing tradition