“ The measure of any desegregation plan is its effectiveness.
On the record before us, it is clear that the Court of Appeals felt constrained to treat the eastern part of metropolitan Mobile in isolation from the rest of the school system, and that inadequate consideration was given to the possible use of bus transportation and split zoning. For these reasons, we reverse the judgment of the Court of Appeals as to the parts dealing with student assignment, and remand the case for the development of a decree 'that promises realistically to work, and promises realistically to work now.' Green v. ”

“ A district court may and should consider the use of all available techniques including restructuring of attendance zones and both contiguous and noncontiguous attendance zones. See Swann, supra, at 22-31, 91 S.Ct., at 1279-1283. ”