Nāʻālehu is a community in Hawaiʻi County, Hawaii, United States. Nāʻālehu is Hawaiian for "the volcanic ashes". It is one of the southernmost communities with a post office in the 50 states of the United States. For statistical purposes, the United States Census Bureau has defined Naalehu as a census-designated place (CDP). The census definition of the area may not precisely correspond to local understanding of the area with the same name. The population was 866 at the 2010 census, down from 919 at the 2000 census.

Hawaii County is a county in the U.S. state of Hawaii in the Hawaiian Islands. It is coextensive with the Island of Hawaii, often called the "Big Island" to distinguish it from the state as a whole. The 2020 Census population was 200,629. The county seat is Hilo. There are no incorporated cities in Hawaii County. The Hilo Micropolitan Statistical Area includes all of Hawaii County. Hawaii County has a mayor–council form of government. In terms of geography, Hawaii County is the most expansive county in the state and the most southerly county in the United States.