The calculated distance (air line) between Tres Marías and Álvaro Obregón is approximately 21 miles respectively 34 kilometers.
By car or train, the actual journey to Álvaro Obregón is certainly longer, as only the direct route (as the crow flies) between Tres Marías and Álvaro Obregón has been calculated here.
Air line (approximately)
34 kilometers
18 nautical miles