UP's route map covers most of the central and western United States west of Chicago and New Orleans. It has achieved this size thanks to purchasing a large number of other railroads, notably the Missouri Pacific, Chicago and North Western, Western Pacific, Missouri-Kansas-Texas, and the Rio Grande (including the Southern Pacific). Currently, Union Pacifc owns 26% of Ferromex while Grupo Mexico owns the remaining 74%.

History

The Union Pacific Railroad was incorporated on July 1, 1862 in the wake of the Pacific Railroad Act of 1862. Under the guidance of its dominant stockholder Thomas C. Durant the first rails were laid in Omaha, Nebraska. They were part of the railroads that came together at Promontory Summit, Utah, in 1869 as the first transcontinental railroad in North America. Subsequently, UP took over the Utah Central extending south from Ogden, Utah, through Salt Lake City, and the Utah & Northern, extending from Ogden through Idaho into Montana, and it built or absorbed local lines that gave it access to Denver and to Portland, Oregon, and the Pacific Northwest. It acquired the Kansas Pacific (originally called the Union Pacific, Eastern Division, though in essence a separate railroad). It also owned narrow gauge trackage into the heart of the Colorado Rockies and a standard gauge line south from Denver across New Mexico into Texas.

UP was entangled in the Crédit Mobilier scandal of 1872. Its early troubles led to bankruptcy during the 1870s, the result of which was reorganization of the Union Pacific Railroad as the Union Pacific Railway on January 24, 1880, with its dominant stockholder being Jay Gould. The new company also declared bankruptcy, in 1893, but emerged on July 1, 1897, reverting to the original name, Union Pacific Railroad. Such minor changes in corporate titles were a common result of reorganization after bankruptcy among American railroads. The recovered railroad was strong enough to take control of Southern Pacific Railroad (SP) in 1901 and then was ordered in 1913 by the U.S. Supreme Court to surrender control of the same. UP also founded the Sun Valley resort in Idaho. In 1996, UP finally acquired SP in a transaction envisioned nearly a century earlier.

Primarily concentrated west of the Mississippi River, UP directly owns and operates track in 23 U.S. states: Arizona, Arkansas, California, Colorado, Idaho, Illinois, Iowa, Kansas, Louisiana, Minnesota, Missouri, Montana, Nebraska, Nevada, New Mexico, Oklahoma, Oregon, Tennessee, Texas, Utah, Washington, Wisconsin, and Wyoming. For administrative purposes, its network is divided into 21 “service units”: Chicago, Council Bluffs, Commuter Operations, Denver, El Paso, Fort Worth, Houston, Kansas City, Livonia, Los Angeles, North Little Rock, North Platte, Portland, Roseville, San Antonio, Saint Louis, Tucson, Twin Cities, Utah, and Wichita. Each “service unit” is further divided into many different subdivisions, which represent segments of track ranging from 300-mile mainlines to 10-mile branch-lines.

Not including second, third, and fourth main line trackage, yard trackage, and siding trackage, UP directly operated some 36,206 miles (58,364 kilometers) of track, as of March 24, 2000. When the additional tracks are counted, however, the amount of track that it has direct control over rises to 54,116 miles (87,091 kilometers).

UP has also been able to reach agreements with competing railroads, mostly BNSF, that allow the railroad to operate its own trains with its own crews on hundreds of miles of competing railroads’ main tracks.

Furthermore, due to the practice of locomotive leasing and sharing undertaken by the Class I railroads, UP locomotives occasionally show up on competitors' tracks throughout the United States, Canada and most recently, Mexico.

Because of the large size of UP, hundreds of yards throughout its rail network are needed to effectively handle the daily transport of goods from one place to another. To reduce overall emissions, Union Pacific is acquiring a new generation of environmentally friendly locomotive for use in Los Angeles basin rail yards.

Among the more prominent rail yards in UP’s system include:

• Bailey Yard, the largest railroad classification yard in the world, located in North Platte, Nebraska.
• The Hinkle Locomotive Service and Repair Facility in Hinkle (Umatilla County), Oregon.
• J.R. Davis Yard, the largest rail facility on the United States’ west coast, in Roseville, California.
• Jenks Shop, one of the largest locomotive overhaul and maintenance facilities in the world, located in North Little Rock, Arkansas.
• Global III Intermodal Facility, a critical interchange hub and loading/unloading terminal for intermodal shipments moving through the Chicago metropolitan area, in Rochelle, Illinois.
• Union Pacific Dallas Intermodal Terminal, a massive $80 million expansion of the railroad's transportation hub outside of Dallas, Texas.