YA fantasy-ish. Present day setting, but barbarian horde invades, journey on river barge

[Hannah]

The premise was implied to be that space-time was broken, so past/future/crazy fantasy elements were being mashed into modern day our world.

Boy in midwestern U.S. suburbia's town is invaded by a barbarian horde. They put everyone in a prison camp guarded by huge vicious turkeys. Boy escapes when a fire breaks out.

He makes his way onto a river barge going down the Mississippi. At some point they are attacked by these wasps that make you crumble into dust when they sting you. They also encounter a submarine that is hosting gladiator battles. He meets a girl on the submarine who is from a city called either "New Rome" or "New Athens".

Later he journeys there - it's some crazy futuristic city - and meets up with the girl again. I can't remember any more.

[Lobstergirl, au gratin]

What year did you read it? Paper book, ebook, other format? Author female or male? Remember the cover? Series or standalone?

[Hannah]

It was a while back. Maybe 10 years ago? It was a paper book, I know I definitely got it from the library, so it might have been on the recent arrivals shelf. I don't remember the cover or the author but it was a standalone novel (or at least at the point that I read it there were no sequels)

[Michele]

Any chance it's Philip Jose Farmer's Riverworld: To Your Scattered Bodies Go/The Fabulous Riverboat series?

[Hannah]

No, afraid not. There weren't any famous people like Mark Twain in it.

[Hannah]

Well, it's been a while. I'm gonna try this one again.

[Rainbowheart]

Firestorm?

Yestermorrow?