The thin orange line of paint traces a winding path though downtown Manhattan neighborhoods like SoHo, Greenwich Village and the Lower East Side. Uneven and wandering, the stripe runs up major avenues and across narrow streets, sometimes prominent, at other times so faint and worn that it is barely visible.

Although it has existed for four years, the paint line has escaped most people’s notice. And among those who have paused to register its presence, few have probably spent much time contemplating its origin. It is, after all, just a simple bit of paint: one more arcane marking in an urban landscape filled with street art and random splashings; a small-caliber mystery in a big city rich with secrets.

“The orange drip that flows through the East Village,” Sharon Jane Smith, 57, mused on Sunday as she gazed at the section of the line that meandered past her East Village shop, A Repeat Performance, on First Avenue near East 10th Street. “I have no idea where that orange drip came from.”

In August a young blogger named Nick Divers posted an essay online revealing that there is more to the paint than immediately meets the eye. He was not the first to figure out what the line signifies, but his posting was circulated through the blogosphere, bringing new recognition to what began as an intentionally quiet statement.