1848 March – The legislature forms Caldwell County from Bastrop and Gonzales counties. The county seat is called Lockhart.
1860 County population is 2,871. There are 1,610 slaves. Community of Fentress is established, originally as Riverside, later changed to Fentress to honor the town's first physician James Fentress.
1870s St. John Colony established by former slaves.
1874 Town of Luling is established. John and James Merriwether and Leonidas Hardeman build a gristmill and a sawmill, later to be known as Zedler's Mills.
1887 The Missouri, Kansas and Texas completes its track between Lockhart and San Marcos.
As of the 2010 United States Census, there were 38,066 people living in the county. 75.8% were White, 6.8% Black or African, 0.9% Asian, 0.8% Native American, 13.1% of some other race and 2.5% of two or more races. 47.1% were Hispanic or Latino. As of the census of 2000, there were 32,194 people, 10,816 households, and 8,079 families living in the county. The population density was 59 people per square mile. There were 11,901 housing units at an average density of 22 per square mile. The racial makeup of the county was 70.13% White, 8.50% Black or African American, 0.61% Native American, 0.34% Asian, 0.03% Pacific Islander, 17.66% from other races, and 2.74% from two or more races. 40.44% of the population were Hispanic or Latino of any race. There were 10,816 households out of which 37.00% had children under the age of 18 living with them, 56.00% were married couplesliving together, 13.30% had a female householder with no husband present, and 25.30% were non-families. 21.20% of all households were made up of individuals and 9.40% had someone living alone who was 65 years of age or older. The average household size was 2.82 and the average family size was 3.28. A Williams Institute analysis of 2010 census data found there were about 5.8 same-sex couples per 1,000 households in the county. In the county, the population was spread out with 28.30% under the age of 18, 8.50% from 18 to 24, 29.80% from 25 to 44, 20.80% from 45 to 64, and 12.50% who were 65 years of age or older. The median agewas 34 years. For every 100 females there were 97.50 males. For every 100 females age 18 and over, there were 92.70 males. The median income for a household in the county was $36,573, and the median income for a family was $41,300. Males had a median income of $29,295 versus $21,595 for females. The per capita income for the county was $15,099. About 10.40% of families and 13.10% of the population were below the poverty line, including 15.10% of those under age 18 and 15.40% of those age 65 or over.
