WALK ON.(The Talk of the Town)

Last summer, Caleb Smith, a thirty-four-year-old librarian at Columbia, came across an old Times story with the headline "navy officer near the end of 4-year project of walking in every street on manhattan." The article, from December, 1954, was about an eccentric sixty-five-year-old named Thomas J. Keane, who, in the course of taking carefully planned weekend strolls, had managed to traverse some three thousand blocks and five hundred miles of Manhattan terrain. Smith, himself an inveterate walker, was then a little more than two years into his own all-encompassing Manhattan project--and, he estimated, about three-quarters of the way done. Why not pick up the pace and aim at finishing on the fiftieth anniversary of his predecessor's achievement?

That was two Sundays ago, and Smith, to commemorate the occasion, invited a handful of friends to watch him walk his last untravelled block--Thirty-third Street between Fifth Avenue and Broadway, at the foot of the Empire State Building. His final stats: thirty-one months, four pairs of shoes, one ex-girlfriend, and one aborted mugging, all culminating in a last, leisurely stride and a pervasive (if unspoken) feeling of "What next?"

You might ask: had Smith, in all his wandering, really never walked past the Empire State Building before? Taskoriented walking, it turns out, is distinct from destination-oriented walking or dog walking--all walking, in fact, that has an alternative purpose. In Smith's grand design, a block remained technically unwalked until he colored it black on his laminated map (Hagstrom, pre-digital edition). Being officially "on the walk" required him to be alone, in possession of a notebook, a camera, and a Sharpie. He instituted the solo rule early, after a frustrating experience spent crossing the West Village with a friend. "I kept saying, 'No, we have to go down this other street,' " he recalled the other day. "And she got impatient."

A few days before he crossed the finish line, Smith made an exception to this rule and allowed a reporter to tag along as he sought out some last, elusive stretches of road up near Inwood: a cul-de-sac off 186th Street called Washington Terrace; the perimeter of Bennett Park, where Fort Washington once lay; Colonel Robert Magaw Place, between 181st and 183rd.

"Obviously, there's some sort of psychological thing going on that I don't quite understand," he said, emerging from a Dunkin' Donuts on 181st Street with a cup of hot coffee--essential, in cold weather, for maintaining the manual dexterity necessary to record his route. Before ...