is atop Mount Washburn, which has interpretive exhibits and an observation deck open to the public. The park also monitors fire from the air and relies on visitor reports of smoke and/or flames. Fire towers are staffed almost continuously from late June to mid-September—the primary fire season. Fires burn with the greatest intensity in the late afternoon and evening. Few fires burn more than , and the vast majority of fires reach only a little over an acre (0.5 ha) before they burn themselves out. Fire management focuses on monitoring dead and down wood quantities, soil, and tree moisture, and the weather, to determine those areas most vulnerable to fire should one ignite. The current policy is to suppress all human-caused fires and to evaluate natural fires, examining the benefit or detriment they may pose to the ecosystem. If a fire is considered to be an immediate threat to people and structures, or will burn out of control, then fire suppression is performed. To minimize the chances of out-of-control fires and threats to people and structures, park employees do more than just monitor the potential for fire. Controlled burns are prescribed fires that are deliberately started to remove dead timber under conditions that allow firefighters an opportunity to carefully control where and how much wood is consumed. Natural fires are sometimes considered prescribed fires if they are left to burn. In Yellowstone, unlike some other parks, there have been very few fires deliberately started by employees as prescribed burns. However, over the last 30 years, over 300 natural fires have been allowed to burn naturally. In addition, firefighters remove dead and down wood and other hazards from areas where they will be a potential fire threat to lives and property, reducing the chances of fire danger in these areas. Fire monitors also regulate fire through educational services to the public and have been known to temporarily ban campfires from campgrounds during periods of high fire danger. The common notion in early United States land management policies was that all forest fires were bad. The fire was seen as a purely destructive force and there was little understanding that it was an integral part of the ecosystem. Consequently, until the 1970s, when a better understanding of wildfire was developed, all fires were suppressed. This led to an increase in dead and dying forests, which would later provide the fuel load for