SOLVED. people arrive in what turns out to be the afterlife after a soda causes the end of humankind [s]

[Diana]

I read this book a few years back. It starts out in a city that keeps getting bigger, where people keep showing up... we eventually realize that this is the afterlife. Something in a major brand soda is killing everyone off. We also follow this woman who is out in the arctic somewhere as she eventually becomes the last person on earth to die.

[Dylan]

The Brief History of the Dead by Kevin Brockmeier

[Diana]

Yes, thank you.