The Federal Bureau of Prisons determines where a defendant is going to serve his or her time. There are many, many factors that go into this "designation," including a defendant's prior criminal history, the facts of the present case, his or her immigration status, and family ties to a particular community. The public defender appointed to the case can give a more-detailed description of the factors that will go into a particular defendant's designation.
The Bureau of Prisons has a web page with descriptions of the various facilities, available here. http://www.bop.gov/locations/locationmap.jsp