The calculated distance (air line) between Sainte-Thérèse and Longueuil is approximately 19 miles respectively 31 kilometers.
By car or train, the actual journey to Longueuil is certainly longer, as only the direct route (as the crow flies) between Sainte-Thérèse and Longueuil has been calculated here.
Air line (approximately)
31 kilometers
17 nautical miles