Where is Humboldt County?

3 Humboldt Counties in 3 states · 158,323 people (2025)

There are 3 counties named Humboldt County in the United States, in California, Iowa and Nevada. The most populous is Humboldt County, California (county seat: Eureka), with 131,647 people in 2025. 2 of them are named after Alexander von Humboldt, Prussian geographer, naturalist and explorer (1769–1859).

Map of the United States showing where all 3 Humboldt Counties are, labeled by state
Every Humboldt County in the United States (red), labeled with its state. Boundaries: U.S. Census Bureau, 2025. Free to use with attribution (CC BY 4.0).

All 3 Humboldt Counties

Sorted by state. Each link opens the county's map.

StateCounty seatPopulation 2025Land area (sq mi)EstablishedNamed after
Humboldt County, CaliforniaEureka131,6473,5681853Alexander von Humboldt
Humboldt County, IowaDakota City9,4094341857Alexander von Humboldt
Humboldt County, NevadaWinnemucca17,2679,6411861Humboldt River

Questions about Humboldt Counties

How many Humboldt Counties are there?

There are 3 Humboldt Counties in the United States, in California, Iowa and Nevada.

Which Humboldt County is the largest?

By population, Humboldt County, California (131,647 people in 2025). By land area, Humboldt County, Nevada (9,641 sq mi).

Which Humboldt County is the oldest?

Humboldt County, California, established in 1853. The newest is Humboldt County, Nevada (1861).

Why are there so many Humboldt Counties?

2 of the 3 are named after Alexander von Humboldt, Prussian geographer, naturalist and explorer (1769–1859). Many counties took their names from the same founders, presidents and generals as new states were organized.

How do I find out which Humboldt County an address is in?

Open the county map of the state: it has a search box for cities, towns and ZIP codes. On a phone, the "what county am I in" tool on our sister site uses your location.

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Other common county names