What's the Name of That Book??? discussion

So, the series has at least 3 or 4 books maybe more. It's set in a world affected by a plague or illness and most of the population is dead. I believe the main character is male, but there is a group of teens traveling across the country to a 'city' that is safe from the illness. Maybe a big tree in the city, which I believe is near the Canadian border. I feel like the title of one of the books had 'dead end' in it. And there was one cover that had a road sign, possibly one of the big yellow diamond ones? I read these between 2004-2008 so early 2000's because I believe I was waiting for the last one to come out.

A long shot - Paradise City by J.B. Stephens?

Natasha, are there zombies?

Or could a celestial event (comets, shooting stars, asteroid smashing into the moon and changing its orbit) have anything to do with the plot?

Are there any PN elements?

Do the books change PoV depending on the volume (ex. Book 1 is from A's pov, book 2 is from B's pov, book 3 is back to A, book 4 is from both A&B's pov etc.)

I don't really remember any zombies, but that could be why I haven't had any luck in finding the books.

I'm pretty sure there wasn't any sort of celestial aspect to it. I believe in the town/city they were traveling to there were scientists trying to work on a cure for whatever illness it was.

And it may have switched between POV's but the male was the main character, so I feel like it would've been switching from chapter to chapter rather than book to book.
I believe the covers always pictured some sort of desolate landscape.

Found it! It's The Big Empty by J.B Stephens! Will edit and move this as soon as I get on my computer.

Great! The Big Empty by J.B. Stephens for the link.