UP meaning in Messaging ?

The Union Pacific Railroad (reporting marks UP, UPP, UPY), legally Union Pacific Railroad Company and simply Union Pacific, is a freight-hauling railroad that operates 8,300 locomotives over 32,200 miles (51,800 km) routes in 23 U.S. states west of Chicago and New Orleans. Union Pacific is the second largest railroad in the United States after BNSF. Union Pacific and BNSF have a duopoly on transcontinental freight rail lines in the Western United States.

Founded in 1862, the original Union Pacific Rail Road was part of the First Transcontinental Railroad project, later known as the Overland Route. Over the next century, UP absorbed the Missouri Pacific Railroad, the Chicago and North Western Transportation Company, the Western Pacific Railroad, the Missouri–Kansas–Texas Railroad and the Chicago, Rock Island and Pacific Railroad. In 1996, the Union Pacific merged with Southern Pacific Transportation Company, itself a giant system that was absorbed by the Denver and Rio Grande Western Railroad, initially maintaining the Southern Pacific name before the newly merged company reverted to the UP moniker. The Union Pacific Railroad is the principal operating company of the Union Pacific Corporation, both headquartered in Omaha, Nebraska.

Additionally, the Union Pacific of late is the last United States based Class l railroad left in the country that has not originated as a merger between separate road names or holding companies and, as such, is currently the oldest operating Class l railroad in the United States. It previously shared this accolade only with the Kansas City Southern Railway though that is now liable to change due to the Kansas City Southern's acquisition by Canadian Pacific Railway on 15, September 2021, however, this is still subject to regulatory approval.