The maximum speed on park roads is 72 kilometers (45 miles) per hour. Slower limits are posted; please observe them. Do not pass or park on curves, and take road dips slowly. Motorized vehicles are restricted to park roadways and are prohibited on all trails. Check with a park ranger before driving the primitive roads. Trail Use. Stay on trails because shortcuts mar the area and can cause erosion and destructive rockslides. Smoking is not allowed on trails because fire is a constant hazard here. Please carry out all your refuse. Camping and Fires. Camping is limited to campgrounds except for backcountry camping, which is by permit only. Building wood and ground fires is prohibited. Fishing Licenses. Fishing licenses are not required. Obtain fishing information from any park ranger. Firearms and Pets. Use or display of firearms is prohibited. Pets must be kept on a leash at all times, and they are not permitted on trails or in public buildings. River Use. A permit is required to float the Rio Grande. At high water float trips are particularly hazardous. No permits are issued for Santa Elena and Mariscal Canyons when the river is at flood stage. Swimming in the river is discouraged because of the dangers, many of which are unseen. Obtain float permits at park headquarters or ranger stations. For information call or write the Superintendent, Big Bend National Park, Texas 79834, (915) 477-2251. Armchair Explorations Selected books, maps, guides, and other publications are offered for sale at the park or through the mail by the Big Bend Natural History Association, Big Bend National Park, Texas 79834. Please write and ask for a free list. Casey, Clifford B. _Mirages, Mysteries and Reality, Brewster County, Texas, The Big Bend of the Rio Grande._ Pioneer Book Publishers, 1972. Deckert, Frank. _Big Bend: Three Steps to the Sky._ Big Bend Natural History Association, 1981. Langford, J.O. with Fred Gipson. _Big Bend, A Homesteader’s Story._ University of Texas Press, 1973. Larson, Peggy. _The Deserts of the Southwest._ Sierra Club Books, 1977. Madison, Virginia. _The Big Bend Country of Texas_ (Revised edition). October House Inc., 1968. Maxwell, Ross A. _The Big Bend of the Rio Grande._ Guidebook 7. Texas Bureau of Economic Geology, 1968. Sonnichsen, C.L. _The Mescalero Apaches_ (Second edition). University of Oklahoma Press, 1973. Tyler, Ronnie C. _The Big Bend: A History of the Last Texas Frontier._ National Park Service, 1975. Warnock, Barton H. _Wildflowers of the Big Bend Country, Texas._ Sul Ross State University, 1970. Wauer, Roland H. _Naturalists’ Big Bend._ Texas A&M Press, 1980. Index