Railroads are the primary means of crossing the continent. The problem is to get from one side to another requires the crossing of national boundaries, which in turn requires treaties. Not all of the nations of North America see eye-to-eye so getting across boundaries, and then being permitted to continue construction is proving difficult.
The major rail lines west of the Mississippi used to reach the First Nation of the Plains (Disputed Territory) from most anywhere in North America. Anyone coming by train stops in Rabid City and travels by stage or horse into the territory.
Union Pacific RR (USA) Council Bluffs, Iowa, USA to Salt Lake City, CoD.
Central Pacific RR (CoD) connects Salt Lake City, CoD to Tong Si, BCA. Southern Star RR (CSA) connects New Orleans, LA, CSA with Sante Fe, RoT, and on to Saint George, CoD. Eventually it will lead to Tong Shi, BCA but construction on this line has all but stopped at this time. Zion Line RR (CoD) connects Saint George, CoD, with Salt Lake City, CoD. Northwestern RR (USA) connects Chicago, IL, USA with the Union Pacific RR (USA) at Council Bluffs, Iowa, USA Elkhorn Line RR (USA) connects to the Union Pacific RR (USA), and heads into the Dakota's terminating at Rapid City.
USA - United States of America CSA - Confederate States of America RoT - Republic of Texas CoD - Commonwealth of Deseret BCA - British California