Subsequent expansion of the Santa Fe Railway encompassed lines from Amarillo to Pecos (1899); Ash Fork, Arizona to Phoenix (1901); Williams, Arizona to the Grand Canyon (1901); the Belen Cutoff from the Pecos line at Texico to Isleta Pueblo, New Mexico, south of Albuquerque, bypassing the grades of Raton Pass (1907); and the Coleman Cutoff, from Texico to Coleman, Texas, near Brownwood (1912).
In 1907, AT&SF and SP jointly formed the Northwestern Pacific Railroad (NWP), which took over several short railroads and built new lines connecting them to form a route from San Francisco north to Eureka, California. In 1928, Santa Fe sold its half of NWP to SP. In addition, Santa Fe purchased the U.S. portion of the Kansas City, Mexico & Orient Railway (the Mexican portion of the line became the Chihuahua-Pacific Railway, now part of National Railways of Mexico).