Kapa'au is an unincorporated community in Hawaiʻi County, Hawaii, United States. Located at the northern tip of the big island of Hawaiʻi, it is celebrated as the birthplace of Kamehameha I.For statistical purposes, the United States Census Bureau has defined Kapa'au 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 1,734 at the 2010 census, up from 1,159 at the 2000 census.