I've extensively studied European History but no clues on American History, so sorry for sounding dumb. I need to define the setting of a "Western" screenplay I'm co-writing. The idea is to have a character travel by train as far as possible, and then travel by horse (cue the usual Western setting). This would mean the railroads aren't completed yet, there's actually cities where he comes from and still (semi)wild lands where he's travelling to. I've tried to do some research but there's limited sources in my city that cover that period. My understanding is that this could happen in the 19th Century but before the Civil War? What sort of year could that be? Is it plausible? And what cities or geographical areas should I look into?
If you need to know exactly what was in existence and when, Jeremy Atack has complete geocoded rail maps for the United States, by year. https://my.vanderbilt.edu/jeremyatack/data-downloads/ This may be overkill, but it tells you exactly where the rails were, down to a fairly absurd level of precision. There are also files for canals and such if you want even more completeness.
My understanding is that this could happen in the 19th Century but before the Civil War?
Pretty much any time prior to 1900 is still plausible. The first transcontinental railroad connecting west coast to east coast wasn’t completed until 1869, half a decade after the Civil War. And even after that it was a single thin ribbon. Someone going to Salt Lake City or Denver would take the railroad to Ogden or Cheyenne and then spend a day or more riding horseback to their final destination. Someone heading a bit more distant like Animas City (Durango) Colorado or Butte Montana could have weeks of riding ahead of them once they left the rail.
Rail development in the West was uneven to say the least. If you take a look at this map of rail in 1890 from the David Rumsey collection, you’ll see even in the last decade of the 19th century, there were still holes in the rail network, and plenty of places that are still 100 miles or more from rail-lines. Though by then, they do tend to be the very harshest of environments: deserts and mountains.
Most westerns are set between 1865 and 1895 as the rails where reaching into the frontier regions. You could go earlier. But then you’re talking about truly unsettled (by caucasians) lands. The late 1840s into the 1850s are when most western states were getting their first real towns. For that matter, Idaho didn’t get their first permanent settlement (Franklin) until 1860. Anything before the Civil War means you’re talking about weeks to months of travel from the railroads to the west. Any time after 1890 and most places are within a day or two of a rail station. So I’d suggest focusing around 1870. With /u/IconicJester ‘s link you should be able to find a place that has the right amount of disconnectedness you’re looking for,