Big Thicket is the name of a heavily forested area in Southeast Texas, United States. While no exact boundaries exist, the area occupies much of Hardin, Liberty, Tyler, San Jacinto, and Polk Counties and is roughly bounded by the San Jacinto River, Neches River, and Pine Island Bayou. To the north, it blends into the larger Piney Woods terrestrial ecoregion of which it is a part. It has historically been the most dense forest region in what is now Texas, though logging in the 19th and 20th centuries dramatically reduced the forest concentration.