Trailblazers had a tough time keeping on track before the West was mapped. A new exhibit at the Library of Congress, "Mapping the North American Plains," documents 347 years of exploration and discovery of our prairies by those early explorers -- cosmographers, soldiers, travelers and scientists. More than 70 maps trace the image and development of the land from the 16th century to the turn of the 20th century. Included in the display are maps drawn by explorers Meriwether Lewis and William Clark, a sketch of the battle of Little Big Horn drawn in 1881 by Sioux Chief Redhorse and a map of the earliest American representation of the Santa Fe Trail by explorer/traveler Zebulon Pike.

The North American Plains extend from Texas to the Laurentian Highlands in Canada, and from the foothills of the Rocky Mountains to the humid lowlands of the Midwest. The maps are mounted in five sections -- maps of North America by 16th- century European geographers; maps by French, English and American explorers; drawings by soldiers for military strategies; a map series by mapping agencies in the United States and Canada; and commercial maps for travel, promotion and business. These maps can be found in the Library of Congress' James Madison Memorial Building, sixth floor, main exhibit hall, on display from 8:30 a.m. to 9:30 p.m. weekdays and to 6 on weekends and holidays. The exhibit will run through November. If you're taking Metrorail, exit the Blue or Orange line at the Capitol South station. Call 287- 8530. For more details.