The completion of the Six Beale Wagon Road Iron Bridges in Indian Territory in 1859-60 was a big deal for Philadelphia's Iron Works and Railway Companies in 1860-61. As an additional example of this fact, see the second "Pencoyd-Murphy "Business Card" noted below. Note the sterograph (photos) showing the first Murphy-Whipple Plan, double intersecting truss, railroad iron bridge built (in 1856), at:
https://bridgehunter.com/pa/montgomery/bh83236/
Please note the second Pencoyd-Murphy “Business Card” text shown below the iron bridge pictures. Again, Pencoyd/Murphy proudly notes their building of ”some seven (sic) other Roadway Bridges which we have constructed for the Beale (Government) Wagon Route to the Pacific.”
This business card was addressed to: Mr. Edward Miller, Chief Engineer of the Pacific Railroad of Missouri, who had held a similar position with the North Pennsylvania Railroad. Miller was one of Philadelphia’s leading railroad engineers that worked as Chief Engineer for railroad construction in Georgia, Missouri and Pennsylvania during his distinguished professional career. In 1858-60 Miller, serving as Chief Engineer, had just completed major railroad extension of the (Missouri-) Pacific Railroad from Jefferson City west to Sedalia, Missouri. As Kansas-Missouri cross-border civil unrest go too dangerous for his family, he returned to Philadelphia by 1861. (Much of this railroad was destroyed during General Sterling Price's Raid into Missouri in October 1864.)
Immediately, Edward Miller again became active in several new railroad expansion projects around Pennsylvania just as the Civil War was beginning. Miller had a sterling professional reputation, as noted in the website below, and he would have been an appealing client for John W. Murphy and A. & P. Roberts & Co. of Philadelphia in early 1861, just as President-elect Abraham Lincoln was coming to town.
https://www.jstor.org/stable/981771?seq=1#metadata_info_tab_contents