Wildland fires play an important ecological role on the nation’s landscapes. Fires have long shaped the composition of forests and grasslands across every region of the United States, including ponderosa pine forests in the Northwest and the Rocky Mountain West, chaparral in the Southwest, sagebrush steppe in the Great Basin, tallgrass prairies in the Midwest, longleaf pine forests in the South, and the pine barrens of the Atlantic Coast. Fires periodically reduce vegetation densities and stimulate seedling regeneration and growth in some species. Wildland fires can be ignited by lightning or by humans, either accidentally or intentionally. As we have described in previous reports from our body of work on wildland fire management, however, various land use and management practices over the past century—including fire suppression, grazing, and timber harvesting—have reduced the normal frequency of fires in many forest and rangeland ecosystems and have reduced these ecosystems’ resiliency to fire. We have reported that these practices contributed to abnormally dense, continuous accumulations of vegetation, which not only can fuel uncharacteristically large or severe wildland fires but also—with more homes and communities built in or near areas at risk from wildland fire—threaten lives, health, property, and infrastructure. In addition, changing climate conditions, including drier conditions in certain parts of the country, have increased the length and severity of wildfire seasons, according to many scientists and researchers. For example, in the western United States, the average number of days in the fire season increased from approximately 200 in 1980 to approximately 300 in 2013, according to the 2014 Quadrennial Fire Review. In Texas and Oklahoma, the average fire season increased from fewer than 100 days to more than 300 during this time frame. According to the U.S. Global Change Research Program’s 2014 National Climate Assessment, projected climate changes suggest that western forests in the United States will be increasingly affected by large and intense fires that occur more frequently. Figure 1 shows the Forest Service’s assessment of wildfire hazard potential across the country as of 2014. Working collaboratively across federal-nonfederal boundaries to address the wildland fire issue can involve any mix of the nation’s 2.3 billion acres of federal, state, local, private, or tribal lands. Historical settlement and development of the nation resulted in the intermingling of lands among these different entities. As we reported in 2008, about 60 percent of the nation’s land is privately owned and managed, and about 30 percent is managed by five federal land management agencies, with the Forest Service and BLM managing the majority of those lands. Of the remainder, about 8 percent of the nation’s land is owned and managed by state and local governments, and about 2 percent is owned and managed by the federal government for purposes such as military installations and water infrastructure. Under the National Forest Management Act and the Federal Land Policy and Management Act of 1976, respectively, the Forest Service and BLM manage lands for various uses such as protection of fish and wildlife habitat, forage for livestock, recreation, timber harvesting, and mineral production. FWS and NPS manage federal lands under legislation that primarily calls for conservation; activities such as harvesting timber for commercial use are generally precluded. As noted, BIA is responsible for the administration and management of lands held in trust by the United States for Indian tribes, individuals, and Alaska Natives. Each of the five agencies has regional or state offices that oversee individual field units. State forestry agencies and other nonfederal entities—including tribal, county, city, and rural fire departments—have primary responsibility for managing wildland fires on nonfederal lands, and share responsibility for protecting homes and other private structures. State and local governments can also adopt laws requiring homeowners and homebuilders to take measures to help protect structures from wildland fires. Regulating land use on nonfederal and nontribal lands is primarily a state and local responsibility. The challenge of balancing the benefits of periodic fires with fire’s negative effects on communities is particularly difficult in the WUI. Development in the WUI increased over the last several decades, in turn increasing the risk to life and property from wildland fire. According to the 2014 Quadrennial Fire Review, 60 percent of new homes built in the United States since 1990 were built in the WUI, which contains 46 million single-family homes, representing about 40 percent of single-family homes in the United States. Most development in the WUI occurs on nonfederal lands, and, according to the National Association of State Foresters, approximately 76,000 communities nationwide are considered to be at risk from wildland fire. According to the National Interagency Fire Center, the average number of structures burned by wildfire each year from 1999 through 2015 was 2,750; in 2015 alone, the total number of structures destroyed by wildfire was 4,636, of which 2,638 were residences. In addition to residential development, other assets that support communities can be located in the WUI, including power lines, highways, and resources that provide economic benefits to communities, such as timber, oil and gas wells, and recreational opportunities. WUI communities can be very different from each other—for example, seasonal resort towns located in valleys, with homes in close proximity and surrounded by fire-prone vegetation, or major suburban or metropolitan areas adjacent to wildlands. The risk each community faces also varies depending on such things as the flammability of the vegetation in and around the community, structure location and building materials, and local land use decisions. While the degree of risk can vary from one place to another, under specific conditions, wildfire can affect people and their homes in almost any location where vegetation is found. Even structures not immediately adjacent to wildland vegetation can be vulnerable because wind can transport embers and ignite homes more than a mile from a fire. Figure 2 provides examples of variation across communities by showing characteristics of the communities included in our review. See appendix II for the full text of this graphic. Federal agencies and nonfederal entities collaborate in a variety of ways to reduce the risk of wildland fire before a potential wildland fire incident occurs, through fuel reduction, fire preparedness, prevention, and education activities. In addition, individuals and communities may take action to mitigate fire risk by, for example, using fire-resistant building materials or building in low-risk areas. Collectively, these activities are generally intended to contribute to helping communities become more fire adapted. Fuel reduction—the removal of flammable vegetation that can fuel fires— can reduce the severity of wildland fires that occur, slow fire spread, or otherwise make fires more manageable. Fuel reduction can occur through mechanical treatment (i.e., thinning of trees and underbrush) or planned ignitions (known as prescribed fires), which often replicate the positive effects of naturally occurring wildfire. Federal agencies have collaborated with nonfederal entities to prioritize, plan, and conduct fuel reduction activities. For example, federal agencies have assisted local communities or counties in developing Community Wildfire Protection Plans— documents that outline ways individual communities plan to reduce their risk from wildland fire, such as by identifying priority areas for fuel reduction. Federal agencies have also funded landscape-scale fuel reduction projects that span multiple jurisdictions and include multiple partners. Federal initiatives involving such projects include the Collaborative Forest Landscape Restoration Program and the Reserved Treaty Rights Lands Program. Preparedness activities can help communities protect themselves during a wildland fire by ensuring they have access to fire suppression equipment, personnel, and emergency dispatch services. To prepare for wildfire seasons, federal agencies, states, and others sign agreements— such as State Cooperative Wildland Fire Management and Stafford Act Response Agreements—to document their commitment to coordinate and exchange personnel, equipment, supplies, services, and funds among the agencies for responding to wildland fires. At the local level, federal land management officials may meet with nonfederal entities, such as local fire department officials, ahead of the wildland fire season to discuss roles and responsibilities for wildland fire response and to train together by simulating incident responses. Prevention activities can reduce the likelihood of fires caused by humans. From 2001 through 2011, approximately 85 percent of wildfires in the United States were human-caused, according to the National Interagency Fire Center. Such fires can occur unintentionally—for example, when people burn leaves or trash or leave campfires unattended—or they may be deliberately set. According to research, communities with effective wildfire prevention programs are likely to have fewer human-caused fire starts. To help provide information about fire prevention, federal agencies work with nonfederal entities. For example, under the Cooperative Forest Fire Prevention program, established under the Smokey Bear Act of 1952, the Forest Service works with the National Association of State Foresters and the Ad Council to develop and distribute materials for the Smokey Bear campaign. Education activities can help reduce risk by helping homeowners and communities understand actions they can take to reduce risk. For example, communities may help minimize their risk by reducing vegetation and flammable objects around structures—an activity often called creating defensible space. They also may help minimize their risk by using fire-resistant building materials in construction and building in low-risk areas. To help provide information about these activities, federal agencies worked with stakeholder groups to develop a guide “designed to help leaders, planners, emergency professionals, and citizens learn the best approaches and programs to help their community become more fire adapted.” Some communities have encouraged the use of voluntary programs aimed at improving fire risk awareness and promoting steps to reduce their risk, such as the Firewise Communities program. In addition, some states have adopted legislation to encourage or require wildfire mitigation in high-risk areas. For example, some state and local governments have adopted laws and ordinances requiring property owners to establish and maintain defensible space. Figure 3 shows various actions federal agencies and nonfederal entities may take to reduce wildfire risk in and around communities.