Amphibians and Reptiles in Castro County: Texas Cooperative Wildlife Collection list of species found in the county.
Butterflies of Castro County, Texas: Information about and pictures of all the known species of butterflies in the county.
Capitol Impact: Castro County: Political, economic, and educational data.
Castro County, Texas - TXGenWeb Project: USGen Web project - Castro County.
Handbook of Texas Online : Castro County: Current and historical information about Castro County.
The Political Graveyard: Castro County: Lists politicians who lived or died in the county.
YBLost: Castro County, Texas: Castro County, Texas public record information.
