Honolulu County, Hawaii

Honolulu County is a county in Hawaii, United States, made up of the entire island of Oʻahu plus the uninhabited Northwestern Hawaiian Islands out to Kure Atoll. It had a population of 1,016,508 at the 2020 census, an estimated 988,703 by 2025, and covers 601 square miles (1,556 km2) of land centred near 21°28′N 157°58′W.

Honolulu is the county seat, and its downtown postal code is 96813. The county is legally the City and County of Honolulu — a consolidated city-county government, so Hawaii has no separately incorporated cities or towns anywhere in the state. All 61 named places on Oʻahu are Census Bureau-defined communities (CDPs), and the county runs on Hawaii-Aleutian Time, which does not observe daylight saving. Its FIPS code is 15003.

Communities in Honolulu County

Sixty-one census-designated places sit inside the county line, from the 350,964-resident Honolulu urban core down to rural hamlets of a few hundred people. None is incorporated — Hawaii law leaves every neighborhood, suburb and country town as an unincorporated CDP governed directly by the city-county. The 27 largest, ranked by 2020 population, are below; dozens more exist along the North Shore, Windward and Waiʻanae coasts.

Two pairs cause confusion. Waipiʻo and Waipiʻo Acres are separate CDPs a mile apart, both near Pearl City — the Acres is the older, hillier subdivision. And ʻEwa Beach and ʻEwa Gentry are both parts of the wider ʻEwa plain but were split into distinct CDPs by the Census Bureau after 2000, so population figures for one do not include the other.

ZIP Codes

• 96813–96822 — downtown Honolulu, Ala Moana and University-area stations, covering the dense urban core
• 96825 — Hawaiʻi Kai, serving East Honolulu’s eastern half
• 96734 — Kailua post office, also serving Lanikai
• 96744 — Kāneʻohe, also serving ʻĀhuimanu and Heʻeia
• 96782 — Pearl City, also serving Hālawa
• 96789 — Mililani Town and Mililani Mauka share one ZIP
• 96706 — ʻEwa Beach and ʻEwa Gentry share one ZIP
• 96792 — Waiʻanae, also serving Māʻili, Nānākuli and Mākaha
• 96786 — Wahiawā, also serving Schofield Barracks and Whitmore Village
• 96762 — Lāʻie, also serving Hauʻula and Kahuku’s Brigham Young University-Hawaii community

A handful of small windward and North Shore places — Punaluʻu, Kawela Bay, Waikane — have no post office of their own and are served by the nearest larger town’s ZIP.

Geography

Oʻahu is a volcanic island built from two shield volcanoes: the Waiʻanae Range in the west, eroded into the county’s highest peak, and the Kōʻolau Range running the island’s spine, separating the wetter Windward side from the drier Leeward and Honolulu sides. The Koʻolau Range’s cliffs (pali) rise straight from the Windward coast, and Nuʻuanu Pali and the H-3 tunnels are the main road crossings between the two sides. Pearl Harbor, a drowned river valley on the south shore, is the island’s largest natural harbor and holds the U.S. Navy’s Pacific Fleet base.

Because it is an island county, Honolulu has no land border with another county. The nearest counties are Kauaʻi County, across the Kauaʻi Channel to the northwest, and Maui County, across the Kaiwi and Kalohi Channels to the east and southeast — both reachable only by air or sea.

Demographics

Honolulu County counted 1,016,508 residents at the 2020 census and an estimated 988,703 by 2025, a decline driven mostly by out-migration tied to housing cost. About 70% of Hawaii’s entire population lives in the county. Honolulu itself and East Honolulu are the two largest communities, at 350,964 and 50,922. Median household income runs close to the statewide figure of roughly $95,000, though it varies sharply by community — Leeward towns like Waiʻanae and Nānākuli sit well below it, while Windward and central Oʻahu suburbs sit above. With 601 square miles of land, the county’s overall density is roughly 1,700 people per square mile, though nearly all of that population is packed into Oʻahu’s southern third.

Economy & Local Life

Government and the military are the county’s two largest employers: the Hawaii state government employs about 66,900 people county-wide, the federal government about 34,700 (much of it tied to Joint Base Pearl Harbor-Hickam, Schofield Barracks and Marine Corps Base Hawaii), and the City and County of Honolulu itself around 18,600. Tourism is the other pillar — Waikīkī in urban Honolulu remains the state’s single biggest visitor draw. The University of Hawaiʻi at Mānoa, the state’s flagship public university, and Tripler Army Medical Center are both major Honolulu institutions. The Honolulu Marathon, held every December, is the county’s largest annual event and one of the largest marathons in the country by finisher count.

History

The Hawaiian Territory created Honolulu County as one of five original counties in 1905; it was reorganized as the consolidated City and County of Honolulu on April 30, 1907, merging city and county government into one body, which it remains today. The name comes from Hawaiian honolulu, generally translated as “sheltered bay” or “calm port,” describing the natural harbor that made the area a trading hub after Western contact. ʻIolani Palace in downtown Honolulu was the seat of the Hawaiian Kingdom until the 1893 overthrow of Queen Liliʻuokalani, and Pearl Harbor’s naval base was the site of the December 7, 1941 attack that brought the United States into the Second World War — both events are central to the county’s history and are marked at preserved sites open to the public.

Getting There

Three interstate highways cross the county despite it being an island with no connection to the mainland system: H-1 runs the length of urban Honolulu and the Leeward side, H-2 branches north to Wahiawā and Schofield Barracks, and H-3 tunnels through the Koʻolau Range to link Honolulu with the Windward side. The Skyline light-rail line, opened in 2023 and still expanding, now runs from East Kapolei toward Downtown Honolulu.

• Kailua — 12 miles northeast of downtown Honolulu
• Kapolei — 20 miles west of downtown Honolulu
• Wahiawā — 22 miles northwest of downtown Honolulu
• Kahuku — 35 miles north of downtown Honolulu

Daniel K. Inouye International Airport (HNL) in Honolulu is the county’s and the state’s main commercial airport, with nonstop service across the Pacific, mainland U.S. and Asia. There is no Amtrak or other mainland rail connection — Oʻahu is reachable only by air or sea.

Frequently Asked Questions

Where is Honolulu County?
It covers the entire island of Oʻahu in Hawaii, plus the uninhabited Northwestern Hawaiian Islands, in the central Pacific Ocean.

What is the population of Honolulu County?
1,016,508 at the 2020 census, an estimated 988,703 by 2025 — about 70% of Hawaii’s total population.

How big is Honolulu County?
601 square miles (1,556 km2) of land, though the county’s total area including surrounding ocean waters is over 2,100 square miles.

What is the county seat of Honolulu County?
Honolulu, which is also Hawaii’s state capital.

How many towns are in Honolulu County?
None are incorporated — Hawaii has no incorporated cities or towns anywhere in the state. Honolulu County instead has 61 census-designated places, from Honolulu itself down to small North Shore and Windward hamlets.

What ZIP codes does Honolulu County use?
Roughly 40 ZIP codes in the 967xx range, from 96701 (ʻAiea) through 96792 (Waiʻanae) and 96813–96826 across urban Honolulu.

Is Honolulu a city or a county?
Both. The City and County of Honolulu is a single consolidated government, so “Honolulu” can mean the urban CDP, the whole county, or the city government depending on context.

More counties in this state: Towns and villages in Hawaii.