It's impossible to tell unless you have a divine revelation. The Bible says that the land was once one land mass at the time of Eden and was later broken up. I believe its in Missouri, God has revealed to a prophet that Eden was located there.
Science also shows us that the land was once one land mass.
I think Iraq is a more likely candidate...I saw a show where the Tigris and Euphrates rivers were in that area and if the water level was lowered quite a bit, that topographic photography they use showed that two other rivers could also have been further along the same route.
Edit: It was under the assumption that the Garden of Eden was a location that was an allegory for the beginnings of humanity...from what they knew at the time.