"The Lanson Screen", a 1936 short story by Arthur Leo Zagat; first published in Thrilling Wonder Stories, December 1936 (available at the Internet Archive); reprinted in Wonder Story Annual, 1952 (also available at the Internet Archive), and in Groff Conklin's classic anthology The Best of Science Fiction aka The Golden Age of Science Fiction.
In this story, an opaque force field of some kind is suddenly created over NYC (or some other major American metropolis, but I'm pretty sure it was NYC). It may have been the result of a lone inventor or a science experiment gone wrong.
The general shrugged. "I can get it for you when I am convinced that you can veil an entire city as you did this one small house. It seems to me impossible, or so tremendous a task, requiring such huge installations, such vast power, that it would be forbiddingly costly."
The physicist's grating, short laugh was contemptuous. "I'll shield New York for you with the same machine I used here, with the same power—storage batteries not larger than those in your car. Their energy is needed for only an instant, to start the complex functioning of forces whose result you have just witnessed. I'll erect a screen for you about Manhattan Island, an ellipsoid as high and as deep as the least axis of the enclosing rivers. Will this satisfy you?"
"If you can do it, and I cannot blast through, it will. When can you get ready?"
"As soon as I can move my machines to the required location, and set them up. Tomorrow night, if you wish."
The screen can only be turned on and off from inside. The demonstration was only supposed to last for ten minutes, but Professor Lanson is accidentally killed before he can turn it off.
Nothing can be done by anybody outside to get through, but I think the field disappears on its own some time (months or years) later.
Sixty years later, somebody figures out how to crack the screen from outside:
The design that presently took pictured form under Howard Cranston's flying fingers was strangely like that which sixty years ago Henry Lanson had called his B machine. But there was a difference. This one could be used from outside the Screen.
With the aid of this, by expanding the radius to include the original barrier, it would be a simple matter to destroy the hemiobloid of impenetrable force that was a city's tomb, to release the force which Lanson had set up.
There's a possibility that the story starts with somebody fishing near the dome created by the field when it first disappears, though I'm not certain.
No, there's nothing about fishing. The story starts with a small scale test of the Lanson screen:
Harry Osborn, First Lieutenant U. S. Army Air Corps, banked his wide-winged bombing plane in an easy, swooping curve. In the distance New York's white pinnacles caught the sun above a blue-gray billowing of twilight ground-haze.
The story is about the people who go into the city afterward and what they find. I'm pretty sure everyone inside was dead from suffocation, dehydration and/or starvation.
"My colleagues of the viewcast service have informed you of the rending of the veil that sixty-two years ago cut off Manhattan Island from the world. They have brought into your homes the awful vision of dead buildings; dead streets strewn with twisted skeletons. You have, I am sure, tried to picture what must have happened there in the tragic days until eternal silence fell and the entombed city had become a vast necropolis. Today, my friends, the searchers found an account of one man's experience, a painstakingly written chronicle of that time. General Flyers is sponsoring the presentation to you of this human, pitiful tale. I will quote from the diary."
There may have been evidence of some fires, but it's also possible that I'm mixing up the bit about deliberately starting fires found in Blish's story.
"You know," Barndon says slowly. "The city wasn't all burned up. Guess the fire burned up all the oxygen and put itself out. That was what killed the people too."
If I recall correctly, it was narrated as a "near future" event (as in, just a few years into the future from the time it was written), and the world had had time to "move on" from the loss of the city.
The story was published in the fall of 1936, and the Screen goes up in May of 1937:
Midnight of May eighth, 1937. An army truck noses into the Holland Tunnel. On its flat bed are two tarpaulin-covered bulks, machinery of some sort. Its driver is crowded against his wheel by the rotund form of a black-clad civilian whose chins hang in great folds on his stained shirt and whose bulging eyes glow with a strange excitement behind thick lenses. The truck comes out on Hudson Street and turns north.