After the Mexican War the United States government initiated an intensive program to, among other things, survey its southwestern boundary. Texas, with its vast size, diversified geographic topography, proximity to northern Mexico, and strategic position on the trade routes to California, gave it a priority for such a survey. In 1848 the first organized effort, supported by the citizens of San Antonio, sent Col. John C. Hays of the Texas Rangers to find a practical wagon road to El Paso. Hays and his Indian guides left San Antonio on August 27. They met thirty-five Texas Rangers under the command of Capt. Samuel Highsmith. After a perilous journey during which the guide lost his way and the party nearly starved, they reached Presidio del Norte, a Mexican village at the junction of the Río Conchos and the Rio Grande. They returned to San Antonio after an absence of 107 days. Hays reported that a practical wagon route to Presidio del Norte existed during all seasons of the year. In December 1848 the United States secretary of war ordered Maj. Gen. William J. Worth to explore the country along the left bank of the Rio Grande to see if there was a suitable route between San Antonio and Santa Fe. With the report of Hays before him Gen. Worth directed Lt. William H. C. Whiting and Lt. William F. Smith, both Army engineers, to investigate the trail to Presidio del Norte to determine if there was such a practical route between El Paso and the Gulf of Mexico.
The expedition left San Antonio on February 12, 1849, with Whiting in command of a force of fifteen men. The escort of nine men included experienced woodsmen and hunters well versed in frontier life. Whiting, only twenty-four years old, had no previous frontier or Indian experience. His guide was Richard A. Howard, who had been with Hays on the previous exploration. Leaving Fredericksberg on February 21, they proceeded northwest across the Llano River and then southwest across the Pecos to the Rio Grande. On March 24, after a narrow escape from an encounter with Apaches west of the Pecos, they arrived at Fort Leaton, near Presidio del Norte. After resting at Fort Leaton they resumed their journey on March 29, traveling up the east bank of the Rio Grande to their destination, Ponce's Ranch, opposite El Paso del Norte. They left the ranch by a different route and went down the Rio Grande for 120 miles, then turned east to the Pecos, which they followed southeast for sixty miles. They crossed over to the Devils River, then to Las Moras Creek, the Nueces River, and the Rio Seco. They arrived in San Antonio, in two parties, on March 21 and 24. Whiting reported that his return route could be made into a practical wagon road for military and commercial purposes between San Antonio and El Paso. The route pioneered by Whiting and Smith was extensively used in later years. A wagon road was constructed by engineers in the summer of 1849 and became known as the lower or southern road. It was used by the United States army, mail stages, Texas cattle drovers, and settlers migrating to New Mexico, Arizona, and California. It is also followed by part of the Southern Pacific Railroad Company's tracks from San Antonio to El Paso.