A hand-drawn copy of a map of the route from Monterey to Saltillo and Mazapil (the original map was sent to the chief engineer in Washington, D. C.) that was surveyed and drawn by Henry Benham between February 1847 and May 1847. This map's key includes the distances from city to city, estimated populations, important trade products or land features, the general direction (bearing), as well as latitudes and elevations based on notes from Josiah Gregg. Listed on the right side of the map is a key for eight known or reported battle grounds in the area and each is labeled on the map with a red number (0-7). Battles are listed as early as the Battles of 1810 and 1811 between Mexicans and Spaniards, and as recent (at the time) as the Battle of Monterey in 1846 and the Battle of Buena Vista in 1847. Also listed in red are routes taken by Generals Santa Anna and José Vicente Miñon around Buena Vista against General Zachary Taylor from February 22 - 23, 1847. The map also has color coded lines to denote water (blue) and roads (yellow). Benham used a prismatic compass to plot out the map and estimated distances by the walk of a horse. [See Gerald Saxon, "Chapter Five: Henry Washington Benham: A U. S. Army Engineer’s View of the U. S. – Mexican War," in Mapping and Empire?: Soldier-Engineers on the Southwestern Frontier, Reinhartz, Dennis, and Saxon (Austin: University of Texas Press., 2005), 130-155.]
