There was a time when literary agents had to live in New York, near the publishing companies, to be successful at their job.
Today with the internet, fax machines and cell phones it's not necessary. An agent can live just about anywhere they please. Some agents start out in the big cities but after they have a client base move out of the lime light to a more family friendly environment.
Agents can send via email or fax any information the editor needs saving them costly travel and postal expenses.
Writers can now collaborate to write a book from opposite ends of a continent. Dave Barry recently did this. He co-authored a couple of children's book with Ridley Pearson. As many of you may know Dave Barry lives in Florida and Ridley Pearson lives in Colorado. They wrote most of the books via email.
Both books are great and have won awards. I recommend them to anyone who enjoys children's literature or fantasy fiction. The first book is called, "Peter and the Star Catchers" the second book is called, " Peter and the Shadow Thieves".
I digress. My point here is for you not to be discouraged by choosing an agent who may be miles away from the big publishing companies. Distance isn't as much of an issue as it once was.
And while you're writing if you decide to co-write a book with a friend who lives far, far away that is doable as well. :0)