One of two maps which accompanied a compendium of government reports on the survey explorations in New Mexico and West Texas in 1849. This map, prepared by Brevet Lieutenent Colonel J. E. Johnston of the Topographical Engineers, presented new information describing the country primarily between San Antonio and El Paso, but also extending east to Austin and north to Fort Washita. Through the explorations of Johnston and the engineers in his command, a supply and potential railroad route was surveyed across southern Texas. This route became the main passageway for soldiers, settlers, and gold seekers. The map also helped to establish the strategic importance of El Paso.
Details include mountains, rivers, roads, reconnaissance routes with dates, some reconnaissance routes with names of leaders, towns, forts, proposed routes, Indian trails, the Emigrants Route, water holes, and forested areas. Wheat calls the map, "a fitting addition to [the] maps which were brought into being by the Mexican War," noting that the surveys conducted by the Topographical Engineers gave "geographical solidity to Texas, as the last act of the Mexican War drama."
This map was included in Lt. Simpson's report of Col. Washington's expedition. From 31st Congress, 1st Session, Senate Doc. #64.