Harris County is named for John Richardson Harris, an early settler of the area.
As of the census of 2000, there were 3,400,578 people, 1,205,516 households, and 834,217 families residing in the county, making it the largest county by population in Texas. The population density was 1,967 people per square mile (759/km²). There were 1,298,130 housing units at an average density of 751 per square mile (290/km²). The racial makeup of the county was 58.73% White, 18.49% Black or African American, 0.45% Native American, 5.14% Asian, 0.06% Pacific Islander, 14.18% from other races, and 2.96% from two or more races. 32.93% of the population were Hispanic or Latino of any race. 7.2% were of German, 6.2% American and 5.3% English ancestry according to Census 2000. 63.8% spoke English, 28.8% Spanish and 1.6% Vietnamese as their first language.
In 2006 Harris County had 3,886,207 residents. This represented 14.3% growth since 2000.
2005 saw Harris county with 37.5% of its population Latino. This represented an increase of over 120,000 in the number of Latinos in the county. 5.5% of the population was Asian. South Asians especially Indian Americans making up one of the fastest-growing immigrant groups in Harris County, with 35,971 counted in the 2000 Census;.. African Americans constituted 18.4% of the county's population, representing a slight decline in percentage. It however meant the total number of African-Americans in the county had risen..
In 2000 There were 1,205,516 households out of which 37.70% had children under the age of 18 living with them, 50.60% were married couples living together, 13.70% had a female householder with no husband present, and 30.80% were non-families. 25.10% of all households were made up of individuals and 5.30% had someone living alone who was 65 years of age or older. The average household size was 2.79 and the average family size was 3.38.
In the county, the population was spread out with 29.00% under the age of 18, 10.30% from 18 to 24, 33.40% from 25 to 44, 19.80% from 45 to 64, and 7.40% who were 65 years of age or older. The median age was 31 years. For every 100 females there were 99.20 males. For every 100 females age 18 and over, there were 97.00 males.
The median income for a household in the county was $42,598, and the median income for a family was $49,004. Males had a median income of $37,361 versus $28,941 for females. The per capita income for the county was $21,435. About 12.10% of families and 14.97% of the population were below the poverty line, including 19.60% of those under age 18 and 12.20% of those age 65 or over.
According to Children At Risk, a local non-profit research organization, 20.8% of the Harris County children live in poverty, 6.5 per 1,000 die before age 1, and 38% drop out of high school.
Many areas in Harris County are served by Metropolitan Transit Authority of Harris County, Texas (METRO), a public transportation agency headquartered in Downtown Houston.
Greyhound Bus Lines operates various stations throughout Harris County.
Two commercial airports, George Bush Intercontinental Airport and William P. Hobby Airport, are located in Houston and in Harris County. The city of Houston operates Ellington Field, a general aviation and military airport in Harris County.
General aviation airports for fixed-wing aircraft outside of Houston include: