The Union Pacific Railroad agreed to buy the Missouri Pacific Railroad on January 8, 1980. Lawsuits filed by competing railroads delayed approval of the merger until September 13, 1982. After the Supreme Court denied a trial to the Southern Pacific, the merger took effect on December 22, 1982. However, due to outstanding bonds of the Missouri Pacific, its full merger into the Union Pacific Railroad did not become official until January 1, 1997.
The merger not being "official," however, did not stop the UP from integrating MP into its system, and locomotives painted in Jenks Blue were soon scattered all over the UP's territory. (SOme were painted in UP colors, but retained MoPac lettering as well.) Which explains how Missouri Pacific MP15DC 1392 was working a UP freight on the Los Angeles River's eastern bank in 1983, with Los Angeles City Hall dominant in the distance. (Los Angeles, California – October 1, 1983)