28 U.S.C. § 545 : US Code - Section 545: Residence

      (a) Each United States attorney shall reside in the district for
    which he is appointed, except that these officers of the District
    of Columbia, the Southern District of New York, and the Eastern
    District of New York may reside within 20 miles thereof. Each
    assistant United States attorney shall reside in the district for
    which he or she is appointed or within 25 miles thereof. The
    provisions of this subsection shall not apply to any United States
    attorney or assistant United States attorney appointed for the
    Northern Mariana Islands who at the same time is serving in the
    same capacity in another district. Pursuant to an order from the
    Attorney General or his designee, a United States attorney or an
    assistant United States attorney may be assigned dual or additional
    responsibilities that exempt such officer from the residency
    requirement in this subsection for a specific period as established
    by the order and subject to renewal.
      (b) The Attorney General may determine the official stations of
    United States attorneys and assistant United States attorneys
    within the districts for which they are appointed.