In depicting human dramas he glimpsed around him, as in “Three A.M.,†1909, Sloan captured not only the nocturnal activities of the lusty, independent women of the city but their tenement surroundings. This iconic painting is in the collection of the Philadelphia Museum of Art.

Early in the Twentieth Century, while American Impressionists continued to record tranquil cityscapes and pastoral vistas and genteel leisure-class activities on canvases filled with color and light, artists of the Ashcan School turned their attention †and dark palettes †to the face of urban life. Heeding the call of their charismatic leader, Robert Henri, this group of talented, rebellious painters depicted the realities of the world around them, principally New York City.

One of the best of the new realists was John Sloan (1871‱951), who made his way from rural Pennsylvania to Philadelphia to Manhattan, where his images of streets, squares, gathering places and city dwellers helped define New York City in the public imagination.

A man of the people and dedicated Socialist, Sloan moved through the vast and rapidly changing metropolis on foot, creating a “pedestrian aesthetic” that captured the rhythms of urban living in intimate images. Particularly as a newcomer to the city, he found compelling human dramas all around him.

“Seeing the City: Sloan’s New York” is on view at the Westmoreland Museum of American Art through April 27. Originally organized by the Delaware Art Museum, where the show opened last fall, the exhibition is curated by the Delaware Museum’s Joyce K. Schiller and associate curator Heather Campbell Coyle. Comprising 115 paintings, drawings, prints and photographs, the exhibition offers an in-depth view of the artist’s years in New York and the city’s effect on his art.

“The Wake of the Ferry No. 2,†1907, is perhaps Sloan’s most famous painting. Art historian Oliver W. Larkin once called it “a masterful design with few elements: the post of the boat, the barrier at its stern, a corner of the upper deck, a lone passenger and the oily harbor water swelling under a thick sky.†The Phillips Collection.

Born in Lock Haven, Penn., and raised in Philadelphia, Sloan studied with Thomas Anshutz and Henri at the Pennsylvania Academy of the Fine Arts and worked as an artist-reporter for The Inquirer and The Press from 1892 to 1903. His job required on-the-spot sketches of fires, accidents and events around the city, which were then turned into newspaper illustrations. He became an expert etcher and also created austere paintings of everyday life around Philadelphia.

Those paintings reflected the painterly styles of artists favored by his mentor, Henri, such as Rembrandt, Hals, Velzquez, Manet and Whistler. Thus, Sloan and other Henri disciples turned not to the broken brushwork, high-keyed palette and bright light of the Impressionists, but to strong paint application and the richer tonalities of the older masters.

Sloan benefited from association with fellow newspaper illustrators William Glackens, George Luks and Everett Shinn, who joined in meetings at Henri’s studio, where activities ranged from discussions about art to masquerades to boxing matches.

Following Henri and other illustrator friends to New York in 1904, Sloan and his mercurial wife, Dolly, settled in Chelsea and he found employment as an illustrator for Century, Collier’s Weekly and Leslie’s Monthly . Believing that knowledge of life was best acquired by spending time with ordinary people, Sloan indefatigably searched for subjects out his windows and on city streets.

In “Six O’Clock, Winter,†1912, Sloan places the viewer in the jostling sidewalk crowd of the modern city at rush hour, as the elevated train cuts through the picture with a powerful thrust above. The Phillips Collection.

Based on his observations, he began to make etchings and paintings of the working-class people and streetscapes, shops and parks in the neighborhood. “I saw people living in the streets and on the rooftops of the city,” he recalled, “and I liked their fine, human, animal spirits.” Sloan adapted the brushy techniques and tonalities of the Old Masters in portraying contemporary life.

His series of etchings, “New York City Life,” 1905, ranged from a group of girls gathered around a street-level kinescope in “Fun, One Cent” to slumbering residents on tenement rooftops in “Roofs, Summer Night.” His undetected glimpses into neighbors’ homes led to depictions of blowzy women in disheveled quarters in the etching “Turning Out the Light,” 1905, and the painting “Three A.M.,” 1909.

As art historian Katherine E. Manthorne observes, Sloan “was fascinated by the down-to-earth, open sexuality of the young, working-class women he found himself surrounded by, and he painted them with gusto.” He knew such images were too frank for arbiters of public taste and was not surprised when they were rejected for display. “With their working-class women in dishabille, [such] pictures&⁷ere too shocking to be exhibited in conservative venues in the early Twentieth Century,” note curators Schiller and Coyle. Sloan did not sell a painting until 1913.

Other early paintings included views of pedestrians window-shopping at night on 23rd Street, like “Picture Shop Window,” 1907‰8, a raucous crowd gathered in Herald Square to witness returns in “Election Night,” 1907, and the memorable “Wake of the Ferry, No. 2,” 1907, with its solitary figure silhouetted against the Hudson River. An avid moviegoer, Sloan applied lessons learned from the silver screen to the composition of many of these early works, in which he “manipulated formal elements” to make at least one figure stand out in crowd scenes.

Dismayed by the rejection of works by his friends for National Academy of Design exhibitions, in 1908 Henri organized a show for himself, Sloan and other realists †dubbed “The Eight” †at Manhattan’s Macbeth Gallery. Aided by hype orchestrated by Henri and Sloan, the show drew big crowds and significant publicity. A traveling version of the show, primarily organized by Sloan, brought national attention to The Eight. (The group was later dubbed the “Ashcan School” when an art critic caustically described their subject matter as “ash cans and girls hitching their skirts.”)

Even after two decades in the city, Sloan reveled in views of the bustling activity †and short skirts †of women he glimpsed in his ambles around the streets, as exemplified by “Subway Stairs,†a 1926 etching. Delaware Art Museum.

The most political of the realists, Sloan joined the Socialist party in 1910, twice ran for the New York State Assembly, and drew for and edited the left-wing magazine The Masses . He attacked social injustices in some of his finest drawings, such as his graphic “The Triangle Shirtwaist Factory Fire” of 1911, but in general tried to keep his art and politics separate.

Following the showing of The Eight, Sloan’s palette lightened as he experimented with Hardesty Maratta’s color system and studied the work of European Modernists at the Armory Show of 1913.

By the time Sloan relocated in 1912 to Greenwich Village, the bohemian and artistic hub of the city, he was able to present himself in “Self Portrait in a Gray Shirt” as the mature and confident artist he had become at age 41.

In one of his frequent, illustrated letters to his great friend Henri, he depicted himself looking through a telescope from his studio toward Dolly, waving a handkerchief from their new apartment.

From his elevated studio, Sloan painted a dramatic, panoramic view of Manhattan, “Rainbow, New York City,” 1913, as well as familiar rooftop vignettes, like the woman in a bright dress hanging her laundry in “Red Kimono on the Roof,” 1912. Both incorporate the high-keyed palette of the Maratta color system.

Continuing his role as a “spectator of life,” “Spring Rain,” 1912, shows an umbrella-toting young woman hoisting her skirt slightly as she crosses the wet pavement in Union Square. In “Carmine Street Theater,” 1912, a disapproving nun eyes a group of youngsters peering into a darkened theater.

“Six O’Clock, Winter,” 1912, places the viewer in midst of a crowd of pedestrians on the sidewalk at rush hour as an elevated train rushes by overhead. The title of an amusing etching, “Education,” 1913, suggests that the young man is teaching his lady friend how to smoke.

Sloan often depicted life he observed on the city’s rooftops, including women hanging their laundry, as in “Red Kimono on the Roof,†1912. The bright palette and complementary colors reflect the artist’s embrace of Maratta’s color system. Indianapolis Museum of Art.

As he achieved some professional success, Sloan spent summers in Gloucester, Mass., and later Santa Fe, N.M. He also began to paint the city from a more elevated, distant point of view. “Jefferson Market,” 1917, retouched 1922, shows the imposing Victorian Gothic building that housed courts and was attached to a jail viewed from the top floor of the artist’s studio on Washington Place. In an even more ambitious, panoramic painting, “The City from Greenwich Village” of 1922, the product of many sketches, Sloan recorded the view south, down Sixth Avenue over the elevated train and low buildings of the Village toward the skyscrapers of Wall Street. Schiller and Coyle speculate that this “thoughtful and thoroughly worked out” view of the metropolis suggests that the artist was “beginning to understand his role as a recorder of history” in a constantly changing city.

A forced move to Washington Square South in 1927 inspired Sloan to photograph his new surroundings, especially changes taking place around Washington Square Park. On view in the exhibition are photos of a woman walking past a construction site on Sixth Avenue, where the artist formerly lived, and views of the construction of a luxury apartment building at 1 Fifth Avenue just beyond Washington Square Arch. He may have used photographs in composing “Wet Night, Washington Square,” 1928, a dramatic view across the park and through the arch to the towering modern building beyond. “The picture reads more as a portrait of a building than as a document of city life,” observe Schiller and Coyle.

After 1928, Sloan painted few fresh images of the city, contenting himself with reconsiderations of such earlier subjects as McSorley’s Tavern and current events, like the destruction of the Jefferson Market jail. When New York University took over his building in 1935, he moved to the Chelsea Hotel on West 23rd Street, where he lived the rest of his life. Many of his later paintings were landscapes of the Southwest, and nudes, albeit sometimes with Manhattan views in the background.

Sloan was president of the Society of Independent Artists from 1918 until his death and made further contributions as an instructor at the Art Students League from 1916 to 1938. Reflecting his encouragement of individuality, his students ranged from Alexander Calder and Reginald Marsh to Barnett Newman and David Smith.

A year after Dolly’s death in 1943, Sloan married a former student, Helen Farr, some 40 years his junior, whose copious notes in his class at the Art Students League led to the publication of the artist’s celebrated Gist of Art in 1939.

Dividing their time between New York and Santa Fe, the couple led a rewarding and productive life until Sloan’s death in 1951.

Thereafter, Helen Farr Sloan returned to teaching and devoted her life to perpetuating the legacy and nurturing the reputation of her husband.

In “Picture Shop Window,†1907‰8, Sloan showed people strolling along the street at night, with special attention to the women in the foreground looking into a brightly lit store. “The silhouette of the woman crouched over to peer at the window’s contents&⁰rompts us to want to do the same,†says art historian Katherine E. Manthorne. Newark Museum.

She donated thousands of Sloan’s works of art, books and archival materials to the Delaware Art Museum, making it the repository of the world’s largest collection of Sloan’s art and extensive archival material. She eventually moved to Wilmington in 1989, where she became a revered figure until her death in 2005. Beyond her donations and inspiration that made the museum the center for Sloan studies, “it was for her personal and unassuming generosity in sharing of herself, of her memories, and of her wisdom that Helen will perhaps be most remembered and most sorely missed,” writes museum executive director Danielle Rice in the catalog.

“Seeing the City: Sloan’s New York” underscores the everlasting importance and relevance of John Sloan’s 40 years of depicting life in New York City. By immersing himself in the urban dramas around him, he became a kind of visual social historian whose art will survive in posterity as a record of life in America’s greatest city.

After closing at the Westmoreland, the exhibition travels to the Smart Museum of Art at the University of Chicago (May 22⁓eptember 14) and Reynolda House, Museum of American Art (October 4⁊anuary 4).

The exhibition is accompanied by a 208-page catalog, titled John Sloan’s New York , with chapters by co-curators Schiller and Coyle, Manthorne and other art historians who illuminate Sloan’s grasp of the geography and social fabric of the city, his interest in social reform, his fascination with motion pictures and his relationship with Henri. Published by Delaware Art Museum in association with Yale University Press, it sells for $50.

An associated exhibition, “Life’s Pleasures: The Ashcan Artists’ Brush with Leisure,” is on view at the Detroit Institute of Arts, March 2⁍ay 25. It features works of New Yorkers at play by Sloan and his compatriots.

The Westmoreland Museum of American Art is at 221 North Main Street. For information, 724-837-1500 or www.wmuseumaa.org .