Callahan, Hood, Coleman, and McCulloch counties. In Texas, this area includes the towns of Weatherford and Mineral Wells; Stephenville lies on the eastern fringe, while Brownwood is on the western edge. The part of this region north of I-20 is sometimes colloquially referred to as the Palo Pinto Mountains; the hills are isolated, rugged, and scenic, with spectacular bluffs along the Brazos River as it flows through the region. Coal mining has historically been an important activity, as bituminous coal deposits are found throughout the region; indeed, the town of Newcastle in Young County was named after the English city of the same name due to the coal connection. In the mid-to-late 19th century, Comanche Indians occupied this area, and it became a flash point for conflict between various groups of white settlers, the Comanche, and the U.S. Cavalry; Forts Belknap and Richardson were built in the area to protect this part of the frontier. Numerous roads cross this region, including US 70 in Oklahoma and I-20, I-30, US 67, US 81, US 82, US 180, US 183, US 281, US 287, and US 380 in Texas. 29d: Grand Prairie A fairly narrow strip dividing the Eastern and Western Cross Timbers, the Grand Prairie differs in physiography, topography, and land use from both of these, as it is much more nearly level and better suited to agriculture. It includes a small part of Love County, Oklahoma (the only part of this region outside of Texas) and passes south through western Cooke County, eastern Wise County, and western Denton, Tarrant, and Johnson counties, and also includes parts of Parker, Erath, Hood, Somervell, Hill, and McClennan counties. This region contains the cities of Fort Worth, Granbury and Denton, although Denton lies on the border with the Eastern Cross Timbers. I-35 and I-35W cross north to south, while US 82, US 380, I-30, I-20, US 377, and US 67 cross east to west; US 81 and US 287 also cross southwest to northeast. 29e: Limestone Cut Plains A broader, southern extension of the Grand Prairie, found only in Texas; it is underlain by limestone rather than sandstone, and serves as a physiological and vegetational transition to the Edwards Plateau, which it borders to the south. All of Hamilton and Coryell counties, large parts of Bell, Lampasas, Mills, Erath, and Bosque counties, and smaller parts of Williamson, Burnet, Brown, Comanche, Hood, Somervell, and McClennan