The county was established by the state legislature on March 13, 1874, and named after Thomas Green, a Confederatebrigadier general. It originally comprised an area over. The original county seat was the town of Ben Ficklin. In 1882, flood waters of the Concho River destroyed the town and drowned 65 people. The county seat was moved to San Angela. In 1883, the town's name was officially changed to San Angelo by the United States Post Office. Tom Green County has a long, narrow strip of land extending to the west. This unusual feature is because Reagan County to the west used to be part of Tom Green County, and the state of Texas required that all counties have a contiguous land route to their county seat. Therefore, the small strip of land served to connect the two main regions. In 1903, the residents of the western section voted to form their own county, while in the same vote it was decided that the connecting strip would remain as part of Tom Green County.
Geography
According to the U.S. Census Bureau, the county has a total area of, of which are land and are covered by water.
As of the census of 2000, 104,010 people, 39,503 households, and 26,783 families resided in the county. The population density was 68 people per square mile. There were 43,916 housing units at an average density of 29 per mi2. The racial makeup of the county was 50.76% White, 5.13% Black or African American, 0.65% Native American, 0.86% Asian, 0.07% Pacific Islander, 12.82% from other races, and 2.39% from two or more races. About 30.71% of the population were Hispanic or Latino of any race, 13.2% were of German, 10.7% American, 8.2% English and 7.2% Irish ancestry according to Census 2000. Of the 39,503 households, 33.00% had children under the age of 18 living with them, 52.10% were married couplesliving together, 11.90% had a female householder with no husband present, and 32.20% were not families. About 27.2% of all households were made up of individuals, and 10.80% had someone living alone who was 65 years of age or older. The average household size was 2.52 and the average family size was 3.09. In the county, the population age was distributed as 26.10% under the age of 18, 12.80% from 18 to 24, 27.10% from 25 to 44, 20.60% from 45 to 64, and 13.40% who were 65 years of age or older. The median agewas 34 years. For every 100 females, there were 93.70 males. For every 100 females age 18 and over, there were 89.90 males. The median income for a household in the county was $33,148, and for a family was $39,482. Males had a median income of $27,949 versus $20,683 for females. The per capita income for the county was $17,325. About 11.20% of families and 15.20% of the population were below the poverty line, including 20.20% of those under age 18 and 11.80% of those age 65 or over.
