By the spring of 2002, the park had become even more of a refuge for Palmer. Eight months earlier, on September 11, Washington watched as acrid smoke billowed from the Pentagon across the Potomac River. People in the streets looked skyward for the last of the four hijacked planes still trying to reach its Washington target. Rumors coursed through the city. The White House was next, maybe the U.S. Capitol. Since that day, the city had been under siege, awash in fear, prompted by security barricades, color-coded warnings, and police carrying automatic weapons. Congress rushed to create the biggest federal bureaucracy since World War II , the Department of Homeland Security. The nation prepared for war in the Middle East. Washington braced for a second wave of terror: a dirty bomb, another anthrax mailing, a suicide attacker on the National Mall or in the tunnels of the Metro that carried hundreds of thousands to work every day. All that seemed a world away beneath the dark green canopy of Rock Creek Park. At the northern end of the park was a popular stable, its horses carrying riders along broad, leafy bridle paths. During the day, visitors picnicked in meadows and on tables perched along the creek. At night, children gazed at the stars near the only planetarium in the national park system. Founded in 1890, Rock Creek Park consists of 2,800 acres and is the country's oldest natural urban park. The heart of the park, the original "pleasure ground" approved by Congress, is where Palmer spotted the object, between the National Zoo and the border of Maryland. The park also includes Fort Stevens, the site of the lone Confederate attack on Washington. By the turn of the century, the park on the edge of the growing capital provided a cooling respite for city dwellers. They would ride in horse-drawn carriages, and relax on giant boulders in the middle of the creek. President Theodore Roosevelt took long walks in Rock Creek Park.
The park remained a pleasure ground, but over the years it had come to symbolize something else. Like many other urban parks, it had become the geographic dividing line of a racially polarized city with its vast wealth, abject poverty, corrupt and incompetent local governance, and some of the most abysmal crime statistics in the nation. On the west side were the city's well-to-do, middle-class, and mostly white neighborhoods—the stately foreign embassies along Massachusetts Avenue, the mansions of Georgetown, the soaring Gothic arches of the Washington National Cathedral, and the exclusive enclave of Cleveland Park with its Victorian homes and wraparound porches. "West of the Park" had become a euphemism for good schools and safe streets.