Clip and project rectangular subset of the map. LONGMIN= and LONGMAX= specify the minimum and maximum longitudes to be included in the map projection. LATMIN= and LATMAX= specify the minimum and maximum latitudes to be included in the map projection. 
proc gproject data=maps.states
              out=reflib.gulf
              longmin=81
              longmax=98
              latmin=25
              latmax=33;
   where density<5;
   id state;
run;