Tycho's father mentioned Las Vegas and a fat mobster there. Las Vegas localization is beyond eastern edge of the Fallout worldmap (and beyond western edge of Van Buren worldmap, 30 miles north-west of Hoover Dam).
Desert Rangers were a faction living in the Nevada area during Vault Dweller times. They were descended from people who had survived the devastation when Great War had happened, likely living among the badlands of Nevada. This small community kept a strong survivalist contingent - so they still had some small arms and books. They probably had something like the cliff-dwelling Indians going on for their town. Tycho was one of them. The Chosen One didn't meet Desert Rangers in western part of Nevada (Fallout 2 area, 2241-2253 year).
In real world there are two class I railroads in Nevada:
- from southern California (Los Angeles region) to Salt Lake City, Las Vegas is stop there,
- from San Francisco and Oakland, via Sacramento, to Salt Lake City, Reno is nod there (there is small one bond railway station in eastern part of New Reno).
Because of Powder Gangs operations line from Hoover Dam to Fort Aradesh become inoperable.