As of the census of 2000, there were 27,507 people, 9,170 households, and 6,290 families residing in the county. The population density was 27 people per square mile (11/km²). There were 10,434 housing units at an average density of 10 per square mile (4/km²). The racial makeup of the county was 78.86% White, 4.30% Black or African American, 6.43% Native American, 2.32% Asian, 0.08% Pacific Islander, 3.92% from other races, and 4.08% from two or more races. 13.92% of the population were Hispanic or Latino of any race. 16.2% were of German, 11.3% English, 9.1% Irish and 7.4% American ancestry according to Census 2000. 91.6% spoke English and 6.2% Spanish as their first language.
There were 9,170 households out of which 33.5% had children under the age of 18 living with them, 50.0% were married couples living together, 13.6% had a female householder with no husband present, and 31.4% were non-families. 25.3% of all households were made up of individuals and 10.1% had someone living alone who was 65 years of age or older. The average household size was 2.58 and the average family size was 3.08.
In the county the population was spread out with 25.1% under the age of 18, 8.0% from 18 to 24, 32.2% from 25 to 44, 22.3% from 45 to 64, and 12.5% who were 65 years of age or older. The median age was 36 years. For every 100 females there were 123.3 males. For every 100 females age 18 and over, there were 130.3 males.
The median income for a household in the county was $29,642, and the median income for a family was $36,056. Males had a median income of $40,072 versus $22,212 for females. The per capita income for the county was $14,573. About 16.40% of families and 20.20% of the population were below the poverty line, including 26.70% of those under age 18 and 8.20% of those age 65 or over.
Local public transit is provided by Redwood Coast Transit, which provides access to Amtrak passenger train (via Amtrak bus) service and Greyhound bus service.
SkyWest Airlines conducts passenger flights to and from Jack McNamara Field Airport. The majority of flights connect to San Francisco International Airport through Arcata-Eureka Airport and vice-versa, although connections are also available to Sacramento and Portland, Oregon.
The Crescent City Harbor serves as a commercial fishing boat basin for Salmon, Shrimp, Tuna, Cod, and Dungeness Crab commercial fishing boats. The harbor is also home to multiple fishing and non-fishing related businesses and harbor governmental offices. The Crescent City Harbor also has several pleasure boat docks.