Ms. Wechsler estimated, optimistically, that her nine-block commute on the High Line took “two, three minutes.”

And yet even in the early morning hours, when runners far outnumber out-of-town photographers, the commuters can upset tranquillity. Briefcases brush against the sunbathing benches. Commuters swat at the vegetation drooping into the walkway. There is music, occasionally, but it is muffled by headphones, clotting into a single garbled note as its owner whirs past.

For the most efficient travelers, a certain code seems to have developed: If possible, keep a safe distance from anyone holding a camera or a map. Plants are to be admired only in passing; the return trip, in the evening rush, is for smelling. The High Line is too crowded for proper speed-walking at those hours, anyway.

In an overstuffed corridor, benches can serve as useful lane dividers, allowing hurried walkers to slide behind them, off the main drag, to elude the crowd. At a small split in the path near West 16th Street, some commuters prefer the narrower stretch at the western edge, avoiding a loop that is often choked with foot traffic near the bathroom and the water fountain.

Smiles and waves, normally frowned upon at street level, are acceptable under certain circumstances. “It’s still New York,” said Moses Soyoola, 24, the founder of a technology start-up in Midtown. “But on the street, I would have completely ignored you if you waved or said hello. Up here, I’m like, whatever, it’s the High Line.”

Some Chelsea residents began commuting almost immediately after the park opened, said Robert Hammond, a co-founder of Friends of the High Line. But the number has accelerated since the introduction of Section Two, he said, with the pathway extended nearer to Midtown residents who work at Google or other companies in Chelsea Market.

Weighed against its alternatives, the High Line would appear to win on aesthetics, too. Jane Potenzo, 63, of Port Washington, N.Y., said she typically walked the High Line to reach Chelsea after taking the Long Island Rail Road to Penn Station, hoping to spot foliage coming into or out of bloom. “It’s the best part of my day,” she said.