"Clockwork Century" is a series of stories by noted steampunk author Cherie Priest.
In Priest's imagination, the American Civil War had extended far beyond its actual historical end in 1865. Here, the year is 1880 and the war has continued to rage due to "English interference." Other things have a new spin as well. For example, the State of Texas discovers oil at Spindletop some fifty years early. This leads to innovations in transportation and the infrastructure associated with the new modes of movement.
The continuing war and technological change has led to boon for some and horror for others. People flee their home states seeking safety. Some find it, some meet terrrible fates.
There are six books in the series thus far, beginning with Boneshakers and concluding with Inexplicables. You can find a full list, including audio versions and eBooks here.
Here is the beginning of an excerpt from Chapter 7, "Unlikely Episodes in Western History" of Boneshakers. You can read the entirety of the excerpt here.
Unpaved, uneven trails pretended to be roads; they tied the nation’s coasts together like laces holding a boot, binding it with crossed strings and crossed fingers. And over the great river, across the plains, between the mountain passes the settlers pushed from east to west. They trickled over the Rockies in dribs and drabs, in wagons and coaches.
Or this is how it began.