While the fort is gone, the Stone Bridge the Army built to cross the Warner wetlands still exists. The Stone Bridge was the first large structure built in the south-central part of Oregon. It was constructed between 16 May and 24 July 1867 by forty men from the 23 Infantry Regiment under the supervision of Captain James Henton. The site chosen for the bridge was a narrow marsh that connects Hart Lake and Crump Lake, two large lakes at the southern end of the seventy-mile long chain of lakes and wetlands known as Warner Lakes. The Stone Bridge is actually a quarter mile long causeway rather than a traditional bridge. It was constructed by hauling basalt boulders and smaller rocks from nearby Hart Mountain and dumping them into the marsh. When it was completed, the causeway was probably several feet above the water level and was wide enough for wagons to pass over it. The Army abandoned the crossing in 1874 when it closed Fort Warner and left the area. In the meantime, the Oregon Central Military Wagon Road had begun using the Stone Bridge to cross the Warner Lakes. However, the road company never maintained it. After the military road was abandoned, local ranchers used the causeway as a cattle crossing for many years. Eventually, the causeway settled into the soft marshy ground, disappearing beneath the water. Today, the Stone Bridge is completely underwater except during periods of drought. As a result, it is very difficult to find. Between 1865 and 1869, the United States Congress awarded land grants to the State of Oregon to pass on to companies constructing military wagon roads. The roads were intended to facilitate the movement of Army units within the state and promote settlement along the routes. Congress eventually authorized the construction of five military wagon roads in Oregon. The first military road was approved by Congress on 2 July 1865. Known as the Oregon Central Military Wagon Road, it was to run from Eugene, Oregon to Fort Boise in Idaho. The Civil War had drained the United States treasury and the State of Oregon did not have a tax base sufficient to support road construction so the government financed the military road projects with land grants. Private companies were specifically chartered to construct the roads. Congress allowed the construction companies to claim three sections of land for every mile of road they built, every odd numbered section in a swath covering three miles (5 km) on either side of the road. As ten-mile (16 km) sections of road were completed, the companies could claim up to thirty sections of land along the route as payment. Once the tracts were patented, the company could sell or lease the land to recover the cost of construction and create profits for its investors.