If a story includes a cross country road trip set in the USA in 1970’s, do the highway and city names need to be accurate / real? If she takes a train cross-country, do the routes need to also be real?
If you use accurate routes and city names, remember to do your research in detail, but when doing a work of fiction, the particular details of the setting can be fictitious as well.
Research is still, of course, needed to make the places sound like a backwater, a fair sized town, what have you -- especially of the region you situate it in -- but many authors have invented places so as to construct exactly what they want.
In a science fiction novel a road trip can be on totally imaginary roads on an imaginary alien planet.
In a fantasty novel a road trip or an epic quest can be on totally imaginary trails and rivers in an imaginary continent or planet.
On the other extreme some stories set on Earth are set in totally real life continents, countries, regions, cities, streets and addresses.
And there are many examples in the wide spectrum between those two extremes.
For example, J.B. Post's An Atlas of Fantasy includes many maps of imaginary places which are supposed to be in the real world instead of fantasy lands like Middle-earth or Narnia.
It has map of Sherlock Holmes' travels in "The Final Problem" which are all real places. Another Sherlock Holmes map shows Baskerville Hall and the moors around it, which are imaginary places in the real Dartmoor, England.
Similarly there is a map of Barsetshire, a fictional County in England in stories by Anthony Trollope.
I discuss the location of Midwich, the fictional English village in the movie The Village of the Damned (1960). In the novel it is based on The Midwich Cuckoos (1957) it is said to be in Winshire, a fictional English county possibly based on Hampshire and its main city Wincester.
I have watched a lot of western movies, especially about the Indian Wars, and I have noticed that the makers of them have no hesitation in rearranging the geography of the west.
My answer here:
has a few example of that.