Tulare County was formed from parts of Mariposa County in 1852. Parts of the county's territory were given to Fresno County in 1856, to Kern County in 1866, to Inyo County in 1866 and to Kings County in 1893.
According to the U.S. Census Bureau, the county has a total area of 12,533 km² (4,839 mi²). 12,494 km² (4,824 mi²) of it is land and 39 km² (15 mi²) of it is water. The total area is 0.31% water.
As of the census2 of 2000, there are 368,021 people, 110,385 households, and 87,093 families residing in the county. The population density is 29/km² (76/mi²). There are 119,639 housing units at an average density of 10/km² (25/mi²). The racial makeup of the county is 58.08% White, 1.59% Black or African American, 1.56% Native American, 3.27% Asian, 0.11% Pacific Islander, 30.79% from other races, and 4.60% from two or more races. 50.77% of the population are Hispanic or Latino of any race.
There are 110,385 households out of which 44.90% have children under the age of 18 living with them, 58.10% are married couples living together, 14.50% have a female householder with no husband present, and 21.10% are non-families. 17.10% of all households are made up of individuals and 7.70% have someone living alone who is 65 years of age or older. The average household size is 3.28 and the average family size is 3.67.
In the county the population is spread out with 33.80% under the age of 18, 10.60% from 18 to 24, 27.60% from 25 to 44, 18.20% from 45 to 64, and 9.80% who are 65 years of age or older. The median age is 29 years. For every 100 females there are 100.00 males. For every 100 females age 18 and over, there are 97.70 males.
The median income for a household in the county is $33,983, and the median income for a family is $36,297. Males have a median income of $30,892 versus $24,589 for females. The per capita income for the county is $14,006. 23.90% of the population and 18.80% of families are below the poverty line. Out of the total people living in poverty, 32.60% are under the age of 18 and 10.50% are 65 or older.