ROBINS AIR FORCE BASE, Ga. -- On Jan. 1, 1973, the U.S. Postal Service assigned Robins Air Force Base the zip code 31098, replacing 31093, which covered all of Warner Robins. It was to be used for all official mail and mail addressed to military quarters located on base. The Warner Robins zip code 31093 was still to used for off base military housing. Ultimately, Houston County got another zip code: 31088.