Hamilton City is a census-designated place in Glenn County, California, United States. The population was 1,759 at the 2010 census, down from 1,903 at the 2000 census. Hamilton City is located 9.5 miles east of Orland, and 10 miles west of Chico at an elevation of 151 feet. The community is inside area code 530. The default prefix used for wired telephones in the Hamilton City area is 826. The postal ZIP Code is 95951.