[1] While only about 20% of Texas counties are generally located within the Houston—Dallas—San Antonio—Austin areas, they serve a majority of the state's population with approximately 22,000,000 inhabitants.

Certain officials, such as the sheriff and tax collector, are elected separately by the voters, but the commissioners' court determines their office budgets, and sets overall county policy.

Cities and counties (as well as other political entities) are permitted to enter "interlocal agreements" to share services (as an example, a city and a school district may enter into agreements with the county whereby the county bills for and collects property taxes for the city and school district; thus, only one tax bill is sent instead of three).

The Federal Information Processing Standard (FIPS) code, which is used by the United States government to uniquely identify states and counties, is provided with each entry.

There have been at least thirty-two counties established by Texas law that no longer exist.