Alligators are native to Texas. Since they got on the endangered list, they have made a remarkable recovery and are now returning to their old haunts. Our ranch butts up to the Colorado River here in south Central Texas very near to where, during the war for independence, Sam Houston and his party crossed on their way east toward what is now the San Jacinto Battleground. He lost several men to alligators.
We haven't seen any up this far north, but we have definitely seen them closer to the coast.