The Army Corps of Topographical Engineers

Army-Corps-of-Topographical-Engineers-During the years following the Mexican War and the settlement of the boundary dispute with England over Oregon, the United States government began looking for routes for a transcontinental railroad.   The responsibility for choosing the route lay with Secretary of War, Jefferson Davis. Davis, a Southerner had the difficult political task of deciding which route would be best. The best ones were the all-weather southerly routes to California crossing Texas, New Mexico and Arizona. There was also Central and Northern routes. There was much political pressure from all areas. Northerners had taken up the cry for the route to begin at Chicago; St. Louis wanted the mid-western route, while the Southerners wanted a New Orleans, Galveston, or Ft. Smith route.

So, Davis determined there would be four transcontinental surveys.  The fifth route, the Oregon Trail, was already marked but the other four would have to be surveyed and mapped. Two of the best routes, the 32nd and 35th Parallels crossed Arizona. Ironically, when the surveys were completed it was determined that all four were suitable for a transcontinental line and would be economically beneficial to areas from Canada to Mexico.  Today, all are major pathways across the country.

In Arizona the future Southern Pacific Railroad and the U.S. 80 (I-8 & I-10) followed the 32nd Parallel via the old Gila Trail. The Santa Fe Railroad and Route 66 (I-40) followed the 35th Parallel on the route surveyed by the U.S. Camel Corps. The Union Pacific went west from Omaha to the San Francisco Bay (the Lincoln Highway, I-80) and the Great Northern Railroad (I-94) went from St. Paul to Seattle.

The task of mapping and surveying the routes fell to the Army Corps of Topographical Engineers, an elite, handpicked group of West Point graduates. Besides surveying routes for transcontinental railroads, they were looking for navigable rivers and wagon roads. Among those engineers were Major William Emory, Lieutenants Amiel Whipple, John Parke, Ned Beale, J.C. Ives, John C. Fremont and Captain Lorenzo Sitgreaves.

Arizona’s highest peak, Mt. Humphreys, 12,633 feet, is named for General Andrew Humphreys who served with the topographical engineers for more than twenty years and was one of the nation’s foremost engineers.

Guides for the expeditions were veteran mountain men of renown including Antoine Leroux, Paulino Weaver, Joe Walker and Kit Carson.

The reports of all four surveys filled twelve volumes.  They gave detailed scientific information plus colorful illustrations from the galaxy of artists who accompanied the engineers. Many are still useful for a basic description of the animals, Indians, geology and flora and fauna or the American West during the 1850’s.

Jefferson Davis mulled over these reports and found the southernmost route for a railroad, along the 32nd Parallel to be the shortest, least costly, and mildest climate.  This drew howls of indignant protest from partisans of the northern routes.  The sectional partisanship was so fanatical and bitter it caused a deadlock in Congress and no further action was taken on a transcontinental railroad until after the Civil War when the Union Pacific and Central Pacific met at Promontory Point, Utah in 1869.

These unsung heroes who mapped the roads west were comparable to the Seven Astronauts of the 1960s who set out to explore another New Frontier. Unfortunately, the magnificent efforts of these early-day soldier-scientists has been overshadowed by the Civil War.

What do you think?

Marshall Trimble

Marshall Trimble is Arizona’s official historian, board president of the Arizona Historical Society and vice president of the Wild West History Association. His latest book is Arizona’s Outlaws and Lawmen; History Press, 2015. If you have a question, write: Ask the Marshall, P.O. Box 8008, Cave Creek, AZ 85327 or e-mail him at marshall.trimble@scottsdalecc.edu