 In particular the Big Thicket region, just north of Houston and Beaumont, has historically been home to the most dense woodlands.The Big Thicket was mostly uninhabited until heavy settlement from the U.S. began in the mid-19th century, and was even used as a refuge by runaway slaves and other fugitives.The Rio Grande valley in South Texas was home to a large palm tree forest when Spaniards first arrived, though today very little of it remains.