Hilo () is a census-designated place (CDP) and the largest settlement in Hawaii County, Hawaii, United States, which encompasses the Island of Hawaii. The population was 44,186 according to the 2020 census. It is the fourth-largest settlement in the state of Hawaii and largest settlement in the state outside of Oahu. Hilo is the county seat of the County of Hawaii and is in the District of South Hilo. The city overlooks Hilo Bay and has views of two shield volcanoes, Mauna Loa, an active volcano, and Mauna Kea, a dormant volcano. Mauna Kea is the site of some of the world's most important ground-based astronomical observatories. The Hilo bay-front has been destroyed by tsunamis twice. The majority of human settlement in Hilo stretches from Hilo Bay to Waiākea-Uka, on the flanks of the volcanoes. Hilo is home to the University of Hawaii at Hilo, ʻImiloa Astronomy Center, as well as the Merrie Monarch Festival, a week-long celebration, including three nights of competition, of ancient and modern hula that takes place annually after Easter. Hilo is also home to the Mauna Loa Macadamia Nut Corporation, one of the world's leading producers of macadamia nuts. Hilo is served by Hilo International Airport. History Around 1100 AD, the first Hilo inhabitants arrived, bringing with them Polynesian knowledge and traditions. Although archaeological evidence is scant, oral history has many references to people living in Hilo, along the Wailuku and Wailoa rivers during the time of ancient Hawaii. Oral history gives the meaning of Hilo as "to twist". Originally, the name "Hilo" applied to a district encompassing much of the east coast of the island of Hawaii, now divided into the District of South Hilo and the District of North Hilo. When William Ellis visited in 1823, the main settlement there was Waiākea on the south shore of Hilo Bay. Missionaries came to the district in the early-to-middle 19th century, founding Haili Church. Hilo expanded as sugar plantations in the surrounding area created jobs and drew in many workers from Asia. For example, by 1887, 26,000 Chinese workers worked in Hawai'i's sugar cane plantations, one of which was the Hilo Sugar Mill. At that time, the Hilo Sugar Mill produced 3,500 tons of sugar annually. A breakwater across Hilo Bay was begun in the first decade of the 20th century and completed in 1929. On April 1, 1946, an 8.6-magnitude earthquake near the Aleutian