Naalehu is a community in Hawaii County, Hawaii, United States. Naʻālehu means "the volcanic ashes" in Hawaiian It is the southernmost community 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. 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.