How many of the five families of snakes that occur in the U.S. are found in the state of Texas?

Snakes occur throughout the entire state of Texas. There are 254 counties in Texas and not one of them is snake free.

The state of Texas hosts four of the five U.S. families of snakes: the Slender blind snakes (Leptotyphlopidae), the Advanced snakes (Colubridae), the largest group; the Old World fixed front fang snakes (Elapidae) and, finally, the New World Pit vipers, the hinge-fanged snakes, a subgroup of the Viper Family (Viperidae).

Within Texas, there are no boas (Boidae). These are the largest and heaviest snake in the world, the green anaconda, is a member of this (Boidae) family.

Specifically, the greatest places to find the various types of snakes in Texas are basically in West Texas, Central Texas, and South Texas.