Few museum exhibits offer an occasion to actually complete an artist’s body of work. But a retrospective of the legendary street photographer Garry Winogrand now at the National Gallery of Art offers a rare exception by displaying haunting, unconventional portraits of mid-20th-century America — many of which weren’t developed or known to exist before his death in 1984.

A tenacious New Yorker who preferred stalking subjects to toiling in the darkroom, Winogrand was part of a generation of shooters including Diane Arbus, Robert Frank and Lee Friedlander who changed the direction of the medium by pushing it into the realm of fine art. His centrifugal compositions, tilted horizons and mysterious detail work juxtaposed the hope and optimism of post-World War II America with a growing sense of anxiety and alienation, according to Sarah Greenough, a National Gallery senior curator and head of the museum’s department of photographs.

Winogrand made no attempt to publish a summary of his work before he died of cancer at 56 — indeed, he was so busy capturing images that he never printed or edited thousands of his own pictures. The exhibit draws on 4,100 rolls of unreviewed, mostly black-and-white film and another 2,500 rolls that weren’t even developed. Other photos are drawn from Winogrand’s archive at the Center for Creative Photography at the University of Arizona.

The 190 images in the show contain iconic subjects such as rodeo cowboys, politicians, gaudy cars and airplanes often in wide shots that strew visual elements about in a random but epic way.

“It was like Walt Whitman: You saw the entirety of American life unfolding in front of you,” said photographer Leo Rubinfien, who worked with Winogrand for a decade and served as a guest curator for the exhibit. “It’s hard to tell whether you’re looking at one man’s view or the spirit of a nation.”

The almost profligate, disorganized way in which Winogrand burned through film searching for spontaneous drama was, in some ways, an antecedent to today’s world of smart phones, selfies and Facebook posts. What was special was the sophisticated imagery he found in seemingly mundane subjects, notes Sandra S. Phillips, senior curator of photography at the San Francisco Museum of Modern Art, in an essay in the catalogue accompanying the exhibit. A photo of people fishing on the Klamath River in California features a boy in the foreground locked in a quizzical pose, with the curve of the river framing the figures from above. An image of a woman looking at her car in a suburban garage uses dark shadows to transform both vehicle and owner into a kind of sculptural frieze.

The first section of the exhibit is devoted to Winogrand’s work in New York City from 1950 to 1971. The urban energy is captured in shots of comely women in pillbox hats, sidewalk protests, nuzzling couples, hippies and soldiers. There’s also a sense of the bizarre in photos such as the one of a well-dressed couple carrying a pair of chimpanzees in children’s clothing in Central Park.

Although he became disillusioned by politicians after the Cuban missile crisis, Winogrand photographed figures such as John F. Kennedy, Eugene McCarthy and Richard M. Nixon in theatrical settings at news conferences, rallies and party conventions. His shots of everyday Americans at political meetings and demonstrations grew more haphazard as the decade wore on, reflecting the mounting social upheaval.

A second section of the exhibit is devoted to Winogrand’s work outside New York, especially in Houston, Dallas, Las Vegas and Los Angeles, where his wide lenses emphasized vast, open spaces. Though the exhibit catalog notes that he concluded the dreams of many Americans were cheap and petty, the photos from this period mix sunlight and humor with kitsch, as if chaos and beauty couldn’t be separated.

The last section is primarily culled from Winogrand’s final years in Los Angeles. Though he was drawn to lively tourist sites, parades, football games and airports, the focus turned bleak and gloomy. Landscapes are austere and often rendered in a harsh light, featuring trash-strewn lots, empty road frontage and distant figures. While critics contend that Winogrand lost his way during this period, the exhibit makes the case he accurately portrayed a growing sense of isolation that was sweeping society.

Winogrand’s admirers see his output as a continuation of the cool, distant objectivism pioneered by Walker Evans during the Great Depression. Rubinfien, who reviewed thousands of photos for the exhibit, said the rejection of sentimentality and artifice enabled Winogrand to capture the immediacy of subjects and the angst of the era.

Garry Winogrand, co-organized by the San Francisco Museum of Modern Art and the National Gallery of Art, is on display through June 8 in the National Gallery’s West Building. The show will continue on to the Metropolitan Museum of Art in New York, the Jeu de Paume in Paris and the Fundación MAPFRE in Madrid.