The largest wildfire in the recorded history of Yellowstone National Park in the United States took place in 1988. Starting as many smaller individual fires, the flames quickly spread out of control due to drought conditions and increasing winds, combining into several large conflagrations which burned for several months. The fires almost destroyed two major visitor destinations and, on September 8, 1988, the entire park was closed to all non-emergency personnel for the first time in its history. Only the arrival of cool and moist weather in the late autumn brought the fires to an end. A total of 793,880 acres (321,272 ha), or 36 percent of the national park, burned at varying levels of severity.
At the peak of the firefighting effort, more than 9,000 firefighters were assigned to the fires in the park, assisted by dozens of helicopters and fixed-wing aircraft which were used for water and fire retardant drops. With fires raging throughout the Greater Yellowstone Ecosystem and other areas in the western United States, the staffing levels of the National Park Service and other land management agencies were inadequate for the situation; more than 4,000 U.S. military personnel were soon brought in to assist in wildfire suppression efforts. The firefighting effort cost $120 million ($330 million in 2025). Structure losses were minimized by concentrating firefighting efforts near major visitor areas, and eventually totaled $3.28 million ($9 million as of 2025). No firefighters died while fighting the Yellowstone fires, although there were two fire-related deaths outside the park.
Before the late 1960s, fires were generally believed to be detrimental to parks and forests, and management policies were aimed at suppressing fires as quickly as possible. However, as the beneficial ecological role of fire became better understood in the decades prior to 1988, a policy was adopted of allowing natural fires to burn under controlled conditions, which proved highly successful in reducing the area lost annually to wildfires.
In contrast, in 1988, Yellowstone was overdue for a large fire, and, in the exceptionally dry summer, many smaller "controlled" fires combined. The fires burned discontinuously, leaping from one patch to another, leaving intervening areas untouched. Intense fires swept through some regions, burning everything in their paths. Tens of millions of trees and countless plants were killed by the wildfires, and some regions were left looking blackened and dead. However, more than half of the affected areas were burned by ground fires, which did less damage to hardier tree species. Not long after the fires ended, plant and tree species quickly reestablished themselves, and native plant regeneration has been highly successful.
The Yellowstone fires of 1988 were unprecedented in the history of the National Park Service and led to many questions about existing fire management policies. Media accounts of mismanagement were often sensational and inaccurate, sometimes wrongly reporting or implying that most of the park was being destroyed. While there were temporary declines in air quality during the fires, no adverse long-term health effects have been recorded in the ecosystem and, contrary to initial reports, few large mammals were killed by the fires, though there was a subsequent reduction in the number of moose.
The largest wildfire in the recorded history of Yellowstone National Park in the United States took place in 1988. Starting as many smaller individual fires, the flames quickly spread out of control due to drought conditions and increasing winds, combining into several large conflagrations which burned for several months. The fires almost destroyed two major visitor destinations and, on September 8, 1988, the entire park was closed to all non-emergency personnel for the first time in its history. Only the arrival of cool and moist weather in the late autumn brought the fires to an end. A total of 793,880 acres (321,272 ha), or 36 percent of the national park, burned at varying levels of severity.
At the peak of the firefighting effort, more than 9,000 firefighters were assigned to the fires in the park, assisted by dozens of helicopters and fixed-wing aircraft which were used for water and fire retardant drops. With fires raging throughout the Greater Yellowstone Ecosystem and other areas in the western United States, the staffing levels of the National Park Service and other land management agencies were inadequate for the situation; more than 4,000 U.S. military personnel were soon brought in to assist in wildfire suppression efforts. The firefighting effort cost $120 million ($330 million in 2025). Structure losses were minimized by concentrating firefighting efforts near major visitor areas, and eventually totaled $3.28 million ($9 million as of 2025). No firefighters died while fighting the Yellowstone fires, although there were two fire-related deaths outside the park.
Before the late 1960s, fires were generally believed to be detrimental to parks and forests, and management policies were aimed at suppressing fires as quickly as possible. However, as the beneficial ecological role of fire became better understood in the decades prior to 1988, a policy was adopted of allowing natural fires to burn under controlled conditions, which proved highly successful in reducing the area lost annually to wildfires.
In contrast, in 1988, Yellowstone was overdue for a large fire, and, in the exceptionally dry summer, many smaller "controlled" fires combined. The fires burned discontinuously, leaping from one patch to another, leaving intervening areas untouched. Intense fires swept through some regions, burning everything in their paths. Tens of millions of trees and countless plants were killed by the wildfires, and some regions were left looking blackened and dead. However, more than half of the affected areas were burned by ground fires, which did less damage to hardier tree species. Not long after the fires ended, plant and tree species quickly reestablished themselves, and native plant regeneration has been highly successful.
The Yellowstone fires of 1988 were unprecedented in the history of the National Park Service and led to many questions about existing fire management policies. Media accounts of mismanagement were often sensational and inaccurate, sometimes wrongly reporting or implying that most of the park was being destroyed. While there were temporary declines in air quality during the fires, no adverse long-term health effects have been recorded in the ecosystem and, contrary to initial reports, few large mammals were killed by the fires, though there was a subsequent reduction in the number of moose.
Fire management policy development in the United States
In the eastern United States, with its significant rainfall, wildfires are relatively small and have rarely posed a great risk to life and property. As settlements moved further west into drier areas, the first large-scale fires were encountered. Range fires on the Great Plains and forest fires in the Rocky Mountains are larger and more destructive than in the east. A number of catastrophic fire events over the years greatly influenced fire management policies.
The worst loss of life in United States history due to a wildfire occurred in 1871 when the Peshtigo Fire swept through Wisconsin, killing more than 1,200 people. The Santiago Canyon Fire of 1889 in California and especially the Great Fire of 1910 in Montana and Idaho contributed to the philosophy that fire was a danger that needed to be suppressed. The Great Fire of 1910 burned 3,000,000 acres (1,200,000 ha), destroyed a number of communities, and killed 86 people; this event prompted various land management agencies to emphasize wildfire suppression. Prior to the 1960s, U.S. Government land agencies, including the National Park Service, generally followed the fire management policies established by the U.S. Forest Service, which oversees the majority of the nation's Forestland. That policy was to suppress all wildland fires.
Before the middle of the 20th century, most forest managers believed that fires should be suppressed at all times. By 1935, the U.S. Forest Service's fire management policy stipulated that all wildfires were to be suppressed by 10 a.m. the morning after they were first spotted. Firefighting crews were established throughout public lands and generally staffed by young men during fire seasons. By 1940, firefighters known as smokejumpers would parachute out of airplanes to extinguish flames in remote locations. By the beginning of World War II, more than 8,000 fire lookout towers had been constructed in the United States. Though many have been torn down due to increased use of airplanes for fire spotting, two are still used each year in Yellowstone. Firefighting efforts were highly successful, with the area burned by wildfires reduced from an annual average of 30,000,000 acres (12,000,000 ha) during the 1930s, to between 2,000,000 acres (810,000 ha) and 5,000,000 acres (2,000,000 ha) by the 1960s. The need for lumber during World War II was high and fires that destroyed timberland were deemed unacceptable. In 1944, the U.S. Forest Service developed an ad campaign to help educate the public that all fires were detrimental, using a cartoon black bear named Smokey Bear. This iconic firefighting bear can still be seen on posters with the catchphrase "Only you can prevent forest fires". Early posters of Smokey Bear misled the public into believing that western wildfires were predominantly human-caused. However, in Yellowstone, 78 percent of fires are caused by lightning, while only 22 percent are human-caused.
However, some researchers in the 20th century argued that this policy should be changed, on the grounds that wildfires clean out the understory and dead plant matter, allowing economically important tree species to grow with less competition for nutrients. Native Americans would often burn woodlands to reduce overgrowth and increase grasslands for large prey animals such as bison and elk. As early as 1924, environmentalist Aldo Leopold argued that wildfires were beneficial to ecosystems, and were necessary for the natural propagation of numerous tree and plant species. Over the next 40 years, increasing numbers of foresters and ecologists concurred regarding the benefits of wildfire to ecosystems. In 1963, a group of ecologists consulted by the National Park Service released the Leopold Report, officially known as Wildlife Management in the National Parks, recommending that wildfires should be allowed to periodically burn to restore the environmental balance in parks. The Wilderness Act of 1964 helped to address the role of fire as a natural part of ecosystems. By 1968, the National Park Service had adjusted its fire management policies that reflected new research. The service determined that fires that started naturally (by lightning) would be permitted to burn if they posed little risk to human life and property. The service also decreed that under prescribed conditions, controlled burns would be deliberately set to restore balance to ecosystems.
From 1972, the National Park Service began allowing natural fires in Yellowstone to burn under controlled conditions. Fires of this type were referred to as prescribed natural fires. Between 1972 and 1987, a total of 235 prescribed natural fires burned a relatively small 33,759 acres (13,662 ha) under the directives of the new policy. Of these, only 15 spread to more than 100 acres (40.5 ha). The five years prior to 1988 were much wetter than normal and this may have reduced the area of the fires during that period.
Contributing factors to the fires
Formal fire record-keeping in Yellowstone began in 1931, when the Heart Lake Fire burned 18,000 acres (7,300 ha). Despite its small extent, it was the largest fire in the period from when the park was created until 1988. Research indicates that only two or three large fires occur on the Yellowstone Plateau every 1,000 years. The previous major Yellowstone fire was in the early to mid-18th century, well before the arrival of the explorers.
Yellowstone forests are dominated by the lodgepole pine and are eventually replaced by other tree species after 80 to 100 years as a forest matures. In Yellowstone, a very short growing season due to high altitude and relatively poor soils allows the lodgepole pine to reach ages approaching three hundred years before other trees such as Engelmann spruce and subalpine fir become established. The lodgepole pines found throughout the Yellowstone Plateau high country grow in uninterrupted dense stands averaging similar ages in various groupings. Though trees normally found in more mature forests do occur, they are not found in large stands as in other forests in the Rocky Mountains. By the 1980s, much of the lodgepole pine forests in Yellowstone were between 200 and 250 years old and approaching the end of their life cycle.
The mountain pine beetle killed a number of trees in the Greater Yellowstone Ecosystem from the late 1960s through the mid-1980s. This created a heterogeneous forest in which old surviving trees were mixed with younger trees of various ages. This mixed stand structure may have provided ladder fuels that contributed to the fires. In addition, the winter season of 1987–1988 was drier than usual, with the Greater Yellowstone Ecosystem receiving only 31 percent of the normal snowpack. However, April and May 1988 were very wet and the abundant moisture greatly aided grass and understory development. By June, the rainfall stopped and little was recorded in the entire Greater Yellowstone Ecosystem for the next four months. By July, the worst drought in the history of Yellowstone National Park began. Grasses and plants which grew well in the early summer soon turned to dry tinder. Relative humidity levels fell further, desiccating the forest. Fuel moisture content in dead and fallen timber was recorded as low as 5%. By mid-August, humidity levels were averaging below 20% and were recorded as low as 6% on one occasion. To compound the lack of rainfall, the majority of Yellowstone's soils are rhyolitic volcanic rocks and soils which have poor moisture retention. A series of strong but dry storm fronts also led to the rapid spread of a number of the largest fires.
Accumulated fuel, old forests, and unabated and exceptionally dry conditions spelled trouble for Yellowstone. However, foresters and fire ecologists predicted a normal fire season for the Greater Yellowstone Ecosystem and anticipated normal rainfall for July. History provided little evidence to suggest that 1988 would be any different from the previous 100 plus years the park had existed. But, as major fires started to break out throughout the Rocky Mountain region, the media began to take notice. Twenty small fires started in Yellowstone by July and of those, eleven went out on their own. The remainder were closely monitored in accordance with the prescribed natural fire policies. By July 15, fires throughout the entire Greater Yellowstone Ecosystem had burned 8,500 acres (3,400 ha) and though this was not out of the ordinary, media focus on fires raging throughout the American west influenced the decision by the park officials to initiate fire suppression efforts on July 15. Within a week of the suppression efforts commencing, the fires had spread to include almost 100,000 acres (40,000 ha) on the parkland alone.
Major fires in Yellowstone in 1988
Almost 250 different fires started in Yellowstone and the surrounding National Forests between June and August. Seven of them were responsible for 95% of the total burned area. At the end of July, the National Park Service and other agencies had fully mobilized available personnel, and yet the fires continued to expand. Smaller fires burned into each other, propelled by dry storms which brought howling winds and dry lightning strikes but no rain. On August 20, the single worst day of the fires and later dubbed "Black Saturday", more than 150,000 acres (61,000 ha) were consumed during one of many intense fires. Ash from the fires throughout the park drifted as far away as Billings, Montana, 60 miles (97 km) to the northeast. The wind-driven flames jumped roads and firelines, and burning embers caused long-range spotting, starting new fires a mile (1.6 km) or more ahead of the main fire fronts. Ground fires raced the fuel ladder to the forest canopy and became crown fires with flames over 200 feet (61 m) high. Throughout the summer, fires made huge advances of 5 to 10 miles (8.0 to 16.1 km) a day, and there were even occasions when more than 2 miles (3.2 km) in one hour were recorded.
Snake River Complex fires
One large group of fires was known as the Snake River Complex. These fires were in the southern section of the park, in the headwaters region of the Yellowstone and Snake Rivers. The largest fire in the group was the Shoshone Fire which was started by lightning on June 23. The prescribed natural burn policy was still in effect, and at first, no efforts were made to suppress this fire. It smoldered with little movement for several weeks, then rapidly started expanding towards the northeast on July 20.