Distance from San Diego to Brownsville The straight line distance is several hundreds of miles shorter than the actual border due to the 'L' shaped borders near Yuma and El Paso, and due to the fact that the Rio Grande River meanders all over south Texas.  The approximate mileage as the crow flies is 1,520 miles, the actual is longer and thus, any accounting practices must consider the surveyed distance, which is said to be 1,989 miles or 3,201 km. Index of ...