According to the 2000 U.S. Census, the county has a total area of 498.51 square miles (1,291.1 km2), of which 475.93 square miles (1,232.7 km2) (or 95.47%) is land and 22.57 square miles (58.5 km2) (or 4.53%) is water, including various rivers and Stockton Lake.
There are 5,685 households out of which 27.80% have children under the age of 18 living with them, 57.50% are married couples living together, 7.90% have a female householder with no husband present, and 31.50% are non-families. 28.10% of all households are made up of individuals and 15.30% have someone living alone who is 65 years of age or older. The average household size is 2.35 and the average family size is 2.86.
In the county the population is spread out with 24.60% under the age of 18, 6.40% from 18 to 24, 22.80% from 25 to 44, 25.40% from 45 to 64, and 20.80% who are 65 years of age or older. The median age is 42 years. For every 100 females there are 95.90 males. For every 100 females age 18 and over, there are 90.50 males.
The median income for a household in the county is $26,694, and the median income for a family is $32,710. Males have a median income of $25,017 versus $17,594 for females. The per capita income for the county is $14,356. 17.40% of the population and 11.60% of families are below the poverty line. Out of the total population, 24.80% of those under the age of 18 and 14.20% of those 65 and older are living below the poverty line.