He and about 14 supporters embarked on the final leg of a 480-mile walk between Boston and Washington Saturday morning, dodging roadside debris and swinging wide around several sidewalk sleepers during the 4.7-mile route to the National Archives - home to the Constitution.
Nirenberg, a 60-year-old professor at Marlboro College, chose his last step alone, in a grassy strip across Constitution Avenue from the pillars and white steps of the Archives.
"This is where it all began," he said quietly to a nearby supporter before pausing, then added, "Or ended."
That comment, expressing concern for the country's founding document, illustrates his motivation to trudge along the shoulder of U.S. Route 1 in a trek that started Dec. 1 in icy New England. He said his conscience was "really screaming out."
"It's somewhat in disbelief I stand here in Washington," Nirenberg told the group, which had grown to about 40 people. "But it's not enough."
"Don't think it's over now," he urged them. "A new phase has begun."
Nirenberg arrived in Washington several days before lawmakers are due to return from a three-week holiday break. He plans to rest a sore ankle and right foot, drink some beer and then deliver a packet of petitions, letters and photographs to the Capitol office of House Speaker Nancy Pelosi.
He hopes the walk will persuade Pelosi and other lawmakers to meet with him in person.
Joining Nirenberg for hundreds of miles was Frank Enneking, 72, who remembers leaping from a narrow roadside onto a chain link fence for protection from speeding cars.
A long, shoulderless bridge across the Susquehanna River was the only stretch of the trip Nirenberg did not walk, Enneking said, climbing instead into the car of a third companion who traveled nearby during periods of the trip.
At first, it seemed like the last leg on Saturday might not draw much attention.
Jack MacConnell, a 70-year-old astronomer on the team operating the Hubble space telescope, was the first one to arrive at the National Arboretum, the kickoff point. He read about Nirenberg's walk on a political Web site and wondered where the nation's activists were.
"There's got to be more people," he said in the empty parking lot. "I thought I'd be lost in a sea of hundreds."
People slowly dripped in - from San Francisco, New Mexico, Ohio and elsewhere.
Jamilla El-Shafei of Kennebunkport, Maine, calls herself the "Chief of Peace," and distributes cards with an emblem resembling a police badge.
"There are a bunch of other people who will be here," she said before the final walk, then remembered, "Oh, they're in jail."
The potential marchers were arrested Friday while protesting the American prison camp at Guantanamo Bay, Cuba on the steps of the Supreme Court.
Those who did arrive were drawn to Nirenberg. He's tall with a bushy mustache and walked evenly and quietly as the crowd grew when it reached the city's downtown. Whistles began blowing around him, a man kept rhythm with a drum, activists sought him out for political discussion.
Maggie Hagen, a retired teacher and ex-nun from Cleveland, drove five hours to make the walk. She saw a video of Nirenberg of his Web site and was drawn to him. She flew to Boston to see him start the journey.
"Oh my god, this man speaks my language," she said while crossing a bridge over a hardscrabble set of railroad tracks. "He speaks for me." "It is disappointing," Hagen added. "We need thousands here."
As the group moved toward the cluttered sidewalks of the National Mall, some opponents made remarks about their signs or yellow ponchos with impeachment slogans.
One motorist yelled: "Oh, poor babies!" Another angrily hollered anti-gay slurs. Supportive honks and waves, however, eclipsed the criticisms.
Passing by a CNN office building, Nirenberg estimated that a half-million cars saw him walking along the highway. Although national news outlets took no note of his walk, he nevertheless sees a chance for his message to get through.
"I wonder how many conversations it started," he said, moments before a passing man offered a thumbs up.
"The conscience just feels like it's been exercised," Nirenberg added. "But it's not over. We reached Washington, but it's not over."
© 2008 Bennington Banner