Mystery Book

So there is this book.. and something made me think of it a few months ago and i've been trying to find it again to re-read it... and I have NO IDEA what it is called or who wrote it or even much about it..
I read it in high school.. It was on one of those summer reading lists that they give you to read before starting the next year and write a report about.. It was the summer i was going into 12th grade. I remember i WANTED to read "The Awakening" by Kate Chopin.. but they didn't have it at the bookstore, so I had to get a different choice and i randomly picked this one..
It was an "end-of-the-world"/futurisitic type novel.. It was in this city that had broken down and there was not much left..lots of crime.. not a lot of food/places to live.. I remember lots of talk of garbage.. The main character was a female.. a single adult female..
I THINK she died in the end..or the world ended.. or something bad happened..

It MAY have had something like "The Last" or the "the End" or something in the title.. but maybe not.. I just don't know..

If you have any ideas.. HELP ME!