Located about 12 miles west of the Camp Houston junction of state highway 50 and U.S. 64 is the Cargill Solar Salt plant. Historians have documented that Nathan Boone and his Dragoons scouted the region during the early 1800s, and the location of these salt flats were known by American Indians who traversed the plains for hundreds of years. In 1935, Ezra Blackmun obtained a loan from a bank in Chicago to establish his Blackmun Salt Works. The harvested salt was of good quality and was sold for retail purchase. After Blackmun retired, Cargill Solar Salt purchased the plant and location and today operates one of the largest salt plants in the United States. The historic salt harvesting equipment remains on the property and visitors can tour the facility by calling in advance for appointments. The flats can be seen for miles up and down the Cimarron River Valley near the Woods and Harper county line.