SAN DIEGO — In the history of American art, Charles Reiffel is probably the best early Modernist painter you’ve never heard of.

Celebrated in his own day for Expressionist landscapes of remarkable verve and complexity, he quickly fell off the national radar screen after his death in 1942, just before turning 80. I was unaware of his work until 2008, when seven paintings turned up — and stood out — in a group show.

Now, however, the artist is back, thanks to an eye-opening museum retrospective. “Charles Reiffel: An American Post-Impressionist” is divided almost evenly between the San Diego Museum of Art and the nearby San Diego History Center, both in the city’s Balboa Park. Together there are 55 paintings, 31 works on paper and four large-scale murals, plus archival material (photographs, letters, pamphlets, a scrapbook, etc.). The venues each show works that span a career lasting half a century.

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Reiffel racked up prizes galore during his lifetime — at the 1910 Corcoran Biennial in Washington, D.C., the 1917 Art Institute of Chicago annual, a 1922 nod at Pittsburgh’s prestigious Carnegie International (the nation’s oldest exhibition of international contemporary art), pan-American surveys in San Francisco and Los Angeles and literally dozens more. His best work rewards consideration in ways that make his original acclaim understandable.

Emblematic of what got people worked up is the show’s breakthrough painting, “Bit of Silvermine — The Old Farmhouse,” a hilly country scene painted in rural Connecticut in 1916. A great, heaving landscape threatens to swallow whole the modest house, sheds, plowed field, wooden fences and other signs of human habitation glimpsed through densely painted trees. This is neither a simple pastoral scene nor a vision of spiritual uplift common to conventional American landscape paintings.

The subject is propelled by a rainbow of vivid color, flecked with stabbed marks of white, that Reiffel laid down in agitated brushwork sliding and scurrying across the surface. The composition’s horizon line is high, further jacking up the compression in the excited scene.

A nearly square format (about 3 feet per side) provides contrasting calm stability for the manic exuberance unfurling inside the frame. With variations, these elements characterize most of Reiffel’s best work as it evolved over the next 25 years.

If there’s a revered artist whose paintings are called to mind, surely it is the much younger Chaim Soutine (1893-1943), the Parisian Expressionist known for extraordinary portraits of aching pathos. But Soutine also painted nearly 200 landscapes in the French Pyrenees village of Céret, where he lived between 1919 and 1922. They teeter at the brink of chaos.

Soutine’s turbulent, thickly painted scenes of rustic life amid convulsive nature are usually darker than Reiffel’s, as if he’s hanging on by his fingernails. Several come right up to the edge of total abstraction, in a way that the American painter’s canvases never do. But as booming industrialization rapidly transformed Europe and America, these artists shared a poignant sense of precarious human existence in a roiling world of natural beauty both delirious and dangerous.

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It’s worth noting too that Reiffel arrived at his mature landscape vision several years before Soutine, who headed off from the urban sophistication of Paris to the south of France as artists like Cézanne, Van Gogh and Matisse had done before him.

Finding refuge in relative isolation likewise motivated Reiffel’s departure from the burgeoning city of New York to a Connecticut village, then finally across the country in 1925 to the modest seaside town of San Diego. And his artistic feat is even more impressive when we learn that, as a painter, Reiffel was almost entirely self-taught.

The division of the show into two parts is a pity, since it inevitably dilutes a full accounting of Reiffel’s distinctive achievement. Still, it’s the largest survey since the artist’s death 70 years ago, and another retrospective is unlikely to happen again soon.

A substantial catalog, deftly researched by independent art historian Bram Dijkstra and with contributions from SDMA curator Ariel Plotek, fills in many blanks in Reiffel’s previously undocumented life. Born in Indianapolis to a German immigrant father and his American wife, he trained in commercial lithography shops, producing posters and advertisements at jobs with several flourishing businesses in Indiana, Ohio and New York.

In 1891 he traveled to England. He spent two years in the East Midlands industrial city of Nottingham, working as a journeyman lithographer at the prominent printer Stafford & Co. With money in his pocket he undertook the first of two extended trips around continental Europe and North Africa, visiting museums and sketching along the way.

As an artist Reiffel was a late bloomer — already in his early 50s when his work began to come together around 1915. No one knows for sure, but he was likely introduced to the European avant-garde in depth at the noisy 1913 Armory Show in New York.

His landscape paintings typically unite the flat stylization familiar from lithography with the tactile paint-handling of Impressionist and Post-Impressionist artists like Claude Monet, Childe Hassam and Van Gogh, plus the shallow, vertically stacked zones of sinuous space familiar in Japanese prints, which were popular among advanced European and American artists. The Expressionist current is all his own.

He usually painted outdoors, a practice common to generations of European and American artists, but in Southern California Reiffel has always been corralled among the large (and often amateur) roster of plein air painters. That bland association is one likely reason his star faded fast after World War II, even though his work blows away routine plein air painting.

To be sure, Reiffel’s art is not inventive in the audacious manner of contemporaneous abstract painting. He’s no Arthur Dove.

Instead, his Expressionist visual language applies the momentum of raw emotion to an orderly process of making pictures. They’re an elegiac corollary to inhabiting the natural world, with all the rhapsodic pleasure and unsettling pain that such a fundamental endeavor entails.

And they are erratic, showing the difficulty of maintaining an artistic practice in the wake of economic collapse. During the grinding Great Depression he turned with frequency to conventional land- and seascape views, in what may have been an effort to appeal to a conservative audience that might buy a pleasant picture of the lovely La Jolla shore. Reiffel’s work of the period often feels restrained. But sometimes, as in a mid-1930s scene of stark houses tightly clustered against the backcountry elements beneath a threatening sky, the power is intact.

As he aged, the rigors of painting in remote areas were increasingly lightened by more easily accessible urban scenes — often shown at twilight, in darkness or in the rain. The 20-foot-tall, unexpectedly elegant civic murals he did under the auspices of the WPA’s Federal Art Project, which put food on his table, show that monumental scale was not the ideal format for an art that thrived on compressed intensity.

Reiffel had been born early in the Civil War and died early in World War II, while his mature work coalesced just before his countrymen began shipping overseas to die in the Marne and at Verdun during the Great War. Perhaps it’s mere coincidence, but this unspeakable trinity marks his life’s major passages. Its emotionally torn ethos thrums in Expressionist landscapes whose enraptured imagery is predicated on animal endurance.