Joo Han, the son of Korean immigrants, runs a Manhattan produce store that looks much as it did when his parents opened it a generation ago, working endless hours to forge a new life, banana by banana, milk carton by milk carton.

But the shop that paved his parents’ path to the middle class can barely cover the rent today. Mr. Han is thinking of closing or selling the business — a step that two nearby Korean grocers are also considering, and that hundreds others have already taken.

For decades, Korean greengrocers have embodied a classic New York type — the immigrant entrepreneur — and become as much a staple of city life as the yellow cab and the pretzel vendor. Spike Lee and Jerry Seinfeld found early inspiration in them. The Rev. Al Sharpton led boycotts against them; Rudolph W. Giuliani’s first mayoral campaign used them as a key symbol.

Now, they are on the wane.

“If you come back next year,” Mr. Han said halfway through a 12-hour shift at his Upper Broadway store, “I might not be here.”