Texas has 254 counties, a number which has not changed since 1931 when Loving County was organized. Loving County had a population of 82 according to the 2010 U.S. census, compared with 164 in 1970 and a peak of 285 in 1940. It is the least-populous county in Texas. In contrast, Harris County has the most residents, with a 2010 population of 4,092,459.

Counties range in area from Rockwall's 148.7 square miles to the 6,192.3 square miles in Brewster, which is equal to the combined area of the states of Connecticut and Rhode Island.

The Texas Constitution makes a county a legal subdivision of the state. Each county has a commissioners court. It consists of four commissioners, each elected from a commissioner's precinct, and a county judge elected from the entire county. In smaller counties, the county judge retains judicial responsibilities in probate and insanity cases.

There are more than 1,200 incorporated Texas municipalities ranging in size from 17 residents in Los Ybanez to Houston's 2,338,187, according to the 2019 population estimates of the Texas Demographic Center. More than 80 percent of the state's population lives in counties meeting the U.S. Census Bureau definition of metropolitan areas.

Texas had 419 cities with more than 5,000 population, according to the state data center. Under law, these cities may adopt their own charters (called home rule) by a majority vote. Cities of less than 5,000 may be chartered only under the general law.