data reflib.states1;
   set maps.us;
   select;
      when (state in (9,23,25,33,44,50))       region=1;
      when (state in (34,36))                  region=2;
      when (state in (10,11,24,42,51,54))      region=3;
      when (state in (1,12,13,21,28,37,45,47)) region=4;
      when (state in (17,18,26,27,39,55))      region=5;
      when (state in (5,22,35,40,48))          region=6;
      when (state in (19,20,29,31))            region=7;
      when (state in (8,30,38,46,49,56))       region=8;
      when (state in (4,6,15,32))              region=9;
      otherwise                                region=10;
   end;
run;