The terrorist attacks of September 11, 2001, and their aftermath left few Americans unaffected. As the federal agency with primary responsibility for protecting and preserving many of the nation's most significant cultural and historic sites, the National Park Service had a unique perspective and role in responding to this tragedy. The most profound personal impact within the Service was no doubt on those employees who either witnessed the attacks firsthand or were directly involved in the immediate response, but every national park was affected to one degree or another.Park Service historians and ethnographers quickly recognized the need to record and preserve the experiences and perspectives of those who had witnessed or responded to the attacks. They conducted more than a hundred oral history interviews with Service employees throughout the country, in parks, regional offices, and the Washington headquarters. These unique interviews reveal the memories and interpretation of the event and aftermath in the words of those directly affected. In addition to conducting interviews, there was also a need to document and evaluate the official response of the National Park Service. With that in mind, I began to research the following questions: How did Service managers and staff respond at the national level and in the regional and park offices? What actions did they take and why? How did the attacks and their aftermath affect the way the Service and the parks operated? How did they affect park resources and the allocation of those resources? What impact did the attacks have on the way park staffs viewed their jobs and the way Americans viewed their parks? And finally, what lessons could the Service learn from this experience? What did the Service's response say about its values and responsibilities?Simply put, my goal was to foster a deeper appreciation and understanding for the way the Service and its employees responded to the attacks and to create a detailed historical record of this unique and significant period in the Service's history. This history is also designed to provide Service managers and policymakers with information they might find useful in responding to future emergencies.Writing this history presented some unique challenges. Many of the major decisions about the response operations were made in phone conversations or in meetings with little or no written record. A scarcity of written records meant a greater reliance on the oral history interviews that National Park Service historians and ethnographers conducted. This approach involved a certain amount of risk: memories can be faulty especially after experiencing such a traumatic event; oral accounts can sometimes be confusing or lack specific details.The September 11 event was truly unique in nature and scope. For the first time in our history, American commercial airplanes were used as terrorist weapons. Never before had a terrorist attack within the United States resulted in so many casualties. The resulting story is complex, involving a broad range of perspectives, activities, and locations. When dealing with such a traumatic and chaotic event, even determining an accurate sequence of events can be difficult. Memories are powerful. Witnesses were often more likely to recall vividly their sense of shock and fear, the acrid smell of burning debris, or their images of wounded victims than to recall factual details. Yet both types of information are important for the historical record. "The lived experience is more complex than subsequent interpretations reveal," explains Mary Marshall Clark, the director of the Oral History Research Office at Columbia University. The personal stories conveyed in the interviews reflect the horror of what witnesses experienced before these stories were turned into a more acceptable narrative.