According to the 2000 U.S. Census, the county has a total area of 573.57 square miles (1,485.5 km2), of which 569.47 square miles (1,474.9 km2) (or 99.29%) is land and 4.11 square miles (10.6 km2) (or 0.72%) is water.
There were 8,743 households out of which 35.20% had children under the age of 18 living with them, 63.10% were married couples living together, 8.00% had a female householder with no husband present, and 25.20% were non-families. 22.10% of all households were made up of individuals and 9.90% had someone living alone who was 65 years of age or older. The average household size was 2.63 and the average family size was 3.07.
In the county the population was spread out with 27.50% under the age of 18, 7.40% from 18 to 24, 28.30% from 25 to 44, 23.90% from 45 to 64, and 12.80% who were 65 years of age or older. The median age was 37 years. For every 100 females there were 100.20 males. For every 100 females age 18 and over, there were 96.30 males.
The median income for a household in the county was $41,886, and the median income for a family was $49,192. Males had a median income of $36,815 versus $21,684 for females. The per capita income for the county was $18,685. About 5.30% of families and 6.80% of the population were below the poverty line, including 8.00% of those under age 18 and 7.80% of those age 65 or over.
Former U.S. SenatorHillary Rodham Clinton (D-New York) received more votes, a total of 2,150, than any candidate from either party in Ray County during the 2008 presidential primary. She also received more votes individually than the entire number of votes cast in the Republican primary in Ray County.