Bastrop County is a county located in the U.S. state of Texas. As of the 2010 census, the population was 74,171. There were 20,097 households out of which 35.90% had children under the age of 18 living with them, 58.50% were married couples living together, 10.50% had a female householder with no husband present, and 26.50% were non-families. 21.50% of all households were made up of individuals and 7.50% had someone living alone who was 65 years of age or older. The average household size was 2.77 and the average family size was 3.23.