Which venomous lizard is the only one native to the United States?

The Gila monster is the only venomous lizard native to the United States. Its range covers parts of the arid Southwest, including Arizona, New Mexico, Nevada, Utah, and California, with the species also extending into the Mexican state of Sonora.

Its venom is delivered through grooves in the lower teeth rather than through hollow, hinged fangs. Gila monsters produce venom in modified salivary glands near the ends of their lower jaws, and chewing helps move the venom into a bite. The venom usually is not fatal to healthy adults, but a bite can cause intense pain, swelling, weakness, and a dangerous drop in blood pressure.

The name “Gila” comes from the Gila River Basin in Arizona and New Mexico. The lizard is slow-moving and spends much of its time sheltering underground or beneath rocks. Monitor lizards and Komodo dragons are sometimes confused with it, but they are not native to the United States and are not members of the same genus.