When you write some books, the geographic logistics are no challenge. Basically you know the main routes even in historical times. A lot of roads were on maps for many years. But when you set a story in the back country of the United States anytime from the 1800s until the 1900s, those roads can be difficult to determine.
I ran into this when I was writing my Oregon historical series. I thought I could get the information from museums, but a lot of them had no idea either. Forget finding an accurate map. Oh, you can find the old ones, those drawn during the time, but map making then was a much less exact science than it is for us in the days of Google and satellites. Often it isn't only roads that don't look right but also misplaced rivers and mountains-- they at least don't move around.
So you want to write a story set back in 1899, which I do, how do you determine what the terrain would be like, what paths the characters might take, what transportation would be possible, or how long it might take?
I have books... lots of books on Arizona history but some rely on those unreliable old maps. Some give rough approximations of directions. A modern gazetteer helps.
It helps that I have been in almost every corner of the state at one time or another. I have photos from all across it, but I wasn't taking notes. When I was in Tucson doing some research in museums, I had not worked out the plot for this book. I had never imagined the need for my hero and heroine to travel from Tucson to Holbrook. My many photos are quite handy but then did the vegetation look the same a hundred years ago? Massive logging, forest fires, and human habitation change a lot.
So as my couple ride their horses north through some of Arizona's most beautiful terrain, I am following along with Google literally and it does help. We printed off some of the maps and my husband put them together to make the route pretty obvious. They are on the bookcase behind me for walking back to consider where I am and where they would be.
To write an historical, I don't have to think I have every detail perfect, but the more I can feel where the characters are, the easier it is for me to write their observations and reactions.
Update: After thinking about how inaccurate maps were back in the times of many historical novels, I emphasized how now we have accurate ones due to so many technical advantages. Listen to this clip from a TV show: inaccurate map of world today. So we can then have maps that are intended to politically influence how we think... What exactly can we trust?
image from the link