Texas Department of Criminal Justice (TDCJ) publishes information on their current inmate population as an Excel (xlsx) file.

Here is the direct download link:

https://www.tdcj.texas.gov/documents/High_Value_Data_Sets.xlsx

Alternatively, you can visit this link and click the "High Value Data Sets" link:

https://www.tdcj.texas.gov/kss_inside.html