----------------------------Original message---------------------------- Does anyone out there have zip code centroids available? We, of course, have the Nat. Health & Nutrition Survey w/ locational info referenced by zip code, and emissions & toxics data referenced by lat & longititude. Easiest choice seems to be to assign cases to their zip code centroids & allocate exposure thusly. Any & all help greatly appreciated. bob mcconnaughey [log in to unmask]