The Southern Victory series by Harry Turtledove. Follows from the South winning the Civil War up through WWII with the US and Confederates being bitter rivals throughout.

Don’t. Civilization kinda fucked the planet and is the reason you live in a post-apocalyptic wasteland.

Why not just say almost 4 years?

If I do a Google search and a Reddit thread comes up with relevant info or discussion, I’ll check it out but I have completely stopped browsing and interacting with it.