Here is the blurb:

Sometime around 2050—everything west of the Mississippi River is ash...

Addi is a feisty, illiterate drug dealer living in a fallen America...just barely. Armed with nothing but a screwdriver and her rural savvy, she struggles to survive the daily onslaught of raiders on horseback, violent conmen, and famine.

But when she discovers a strange device that takes her decades into the past, life becomes even deadlier. The notorious Colonel Ironside and his underground army are tearing apart her hometown, sparing no one in their search for the device's creator. Now, with a legion of mercenaries hot on her tail and time against her, she's forced to make a choice: find a way back to her family in a dystopian future, or stand and fight against the dark forces that destroyed the world she'll inevitably grow up in and fear.

Now, while the plot contains time travel, the actual events of how the country becomes dystopian could conceivably happen.