WHEN THE AMON CARTER MUSEUM first opened, in 1961, the compact modernist temple perched on a Fort Worth hillside seemed little more than an elegant cenotaph to its late benefactor, local publishing and oil magnate Amon G. Carter, Sr. Crammed with his collection of paintings and bronzes by Western artists Frederic Remington and Charles Marion Russell, the Carter was, as its architect, Philip Johnson, later remarked, “never intended to be a real museum.” Expectations quickly changed, however, under its first director, the late Mitchell Wilder, who in Fort Worth in the sixties did what Alfred Barr had done in New York in the thirties with the Museum of Modern Art: He created an entirely new genre of art museum. Expanding the Carter’s franchise to embrace early-nineteenth-century Hudson River School landscapes and twentieth-century Taos School abstractions—and amassing one of the world’s premier collections of fine-art photographs and Western documents—Wilder not only placed Amon Carter’s cowboy art in the broad sweep of American art but also set American art and thought in the context of our nation’s defining enterprise, the conquest and settlement of the West. Less oriented to the eastern seaboard and Europe than its peer museums of American art, more catholic and intellectually fecund than any museum of Western art, the Amon Carter Museum became known to scholars and the cognoscenti as the little museum bursting with big ideas.”

“We like to say that we were doing American studies before American studies even existed,” says the Carter’s current director, Rick Stewart, who reopened the museum this fall after a two-year, $39 million, 90,000-square-foot expansion that tripled the previous gallery space and culminated in a sprawling septet of inaugural exhibitions, all drawn from the Carter’s own collections. Boasting American art icons like Martin Johnson Heade’s balefully transcendent 1868 Thunder Storm on Narragansett Bay (sui generis among American nineteenth-century landscapes) and Thomas Eakins’ 1885 Swimming (arguably the apogee of American figurative painting) and bolstered by scores of new acquisitions such as Stuart Davis’ masterful modernist still-life Egg Beater No. 2 (1928), the Carter is effectively going public after decades of relatively obscure excellence.

Philip Johnson, the New York-based architect who has been the Pied Piper of Texas’ architectural tastes for half a century, provided most of the sizzle when the Carter opened forty years ago. But in reprising his design role, the irrepressible nonagenarian had the wisdom to make news by not making news. The augur of the age of celebrity architecture has created instead a marvel of stealth architecture, a low-profile, triangular monolith (shaped to fit the skewed convergence of Camp Bowie Boulevard and Lancaster Avenue) of mocha-hued Arabian granite that shimmers like a desert mirage behind the museum’s original five-arched portico. The trick is so slick that the new addition actually seems to vanish entirely as one approaches the 1961 facade (an underrated triumph of modern classicism that presaged and complements its revered downslope neighbor, Louis Kahn’s Kimbell Art Museum).

Inside, visitors begin where the West—or the West of popular imagination—began, with Amon Carter’s collection of Remingtons and Russells, which have been restored to the lobby gallery, along with Johnson’s original Burmese teak paneling. Carter’s interest in art never strayed beyond the twin avatars of the cowboy genre, but within his narrow field he bought only the best. “Carter was way ahead of his contemporaries in his eye for quality,” Stewart says, a claim substantiated by works like Remington’s landmark 1889 painting, A Dash for the Timber, a cowboy-and-Indian chase scene so cinematic that it looks like it was filmed in Todd-AO.

Russell’s predictable sentimentality and Remington’s predictable theatricality may have served as the models for the twentieth century’s reel West, but visitors to the Carter soon find a considerably more complex and nuanced picture. The new addition’s single, rather modest architectural flourish is a minimalist two-story atrium, clad with the same fossil-flecked limestone as the original arcade and capped with a domed skylight. A divided staircase leads to the second-floor galleries and a procession of first-rate works by familiar American masters—punctuated by entirely unexpected American masterpieces. The marquee attractions include Thomas Cole’s Edenic vision of New Hampshire’s White Mountains, The Hunter’s Return (1845); Winslow Homer’s post-Civil War feel-good pastoral, Crossing the Pasture (1871-72); John Singer Sargent’s characteristically dashed-off yet exquisitely subtle portrait of a storied American beauty, Alice Vanderbilt Shepard (1888); and Marsden Hartley’s pioneering abstraction painted in Berlin in 1914, American Indian Symbols, a striking East-meets-West merger of German Expressionism with stylized tepees and feathered headdresses. But the unexpected pleasures are also a measure of the Carter’s quality; the inevitable John Frederick Peto and William M. Harnett trompe l’oeil still-lifes are joined by the extraordinary Wrapped Oranges (1889) by Eakins’ student William J. McCloskey, who actually specialized in painting tissue-wrapped oranges. Set against a black backdrop, the almost incandescent oranges and the meticulously rendered translucent tissue combine the stark, metaphysical mystery of a seventeenth-century Spanish still-life with the geometric materiality of Cézanne’s apples.

Nothing, however, illustrates the Carter’s innovative eye so much as its vast photography collection. Mitch Wilder, himself an accomplished photographer, stole a march on the market, acquiring the entire estates of personal friends like groundbreaking colorist Eliot Porter and Navajo chronicler Laura Gilpin at a time when most museums ignored, if not actively disdained, the medium; the Carter has gone on to assemble about thirty thousand exhibition-quality prints and a couple hundred thousand negatives and related documents. While most of the wealth is kept in state-of-the-art cold-storage vaults in an enormous new basement complex, the new galleries dedicate enough real estate for five inaugural photography exhibits and a “learn more” gallery with examples of various printing techniques. The central survey, “Masterworks of American Photography” (on view through March 3), pushes beyond the risk-taking evident in works like the McCloskey, not so much challenging accepted standards as setting them. The usual shopping list—Ansel Adams, Walker Evans, Dorothea Lange, Edward Steichen, Paul Strand, Edward Weston—isn’t overlooked, but that this isn’t the standard textbook overview is quickly established by Two Women Posed With a Chair (1850), by Albert Southworth and Josiah Hawes. The oversized daguerreotype is so naturalistically lit and casually animated that it defies expectations of a technique that consistently produced stilted, harshly two-dimensional results; only the sitters’ grim early Victorian hairdos and prim lace collars betray the image’s origins in photography’s infancy. And in a medium whose canon has yet to be firmly set, the Carter nurtures the reputations of lesser-known masters like Karl Struss, who in the mid-1910’s produced a vanguard series of New York views (the Carter owns thousands of Struss prints and negatives). Struss’s The Avenue-Dusk (1914) was shot in the then-prevailing soft-focus pictorial style, but the streetlights that seem to stream in effervescent bubbles over the vintage Fifth Avenue traffic jam give the twilight scene a science-fiction look as well as a precocious abstract quality.

If the Carter’s collections insist on a fresh look at American art, they even more aggressively challenge the myths and orthodoxies of the history of the West. “Aesthetics and content are equally important,” Stewart says of the museum’s collections, which also represent a remarkable mine of raw historical documentation. “Common Ground: Settling Colorado,” an exhibit drawn from the Fred and Jo Mazzulla collection of 10,000 historical photographs (on view through March 31), chronicles the often surrealistic, post-gold rush transformation of the state that was simultaneously inspiring the virginal mountain panoramas of Thomas Moran and Albert Bierstadt. What Manifest Destiny really meant was scenes like William Henry Jackson’s early 1880’s vista of a freshly laid rail line snaking through the blasted, lifeless Grand Canyon of the Arkansas River, an image accompanied by others of huge industrial smelting complexes, chintzy Victorian parlors, packed dry-goods stores, immaculately dressed schoolchildren, tourists (hunters, fishermen, and the fashionable ladies captured in an 1895 amateur print while sightseeing in the South Platte Canyon), and finally, the new machines in the garden, cars parked at a pioneering 1923 auto campground in the foothills of the still scenic but no longer pristine Rockies.

The conquest had more brutal costs. Despite the paucity of evidence in most museums, nineteenth-century American artists didn’t overlook the original snake in the American Eden. John Quincy Adams Ward’s intimate but heroic bronze figure of an African American slave, The Freedman, cast (sometime after 1863) to commemorate black soldiers killed fighting for the Union, still wears a braceletlike legacy of bondage: a miniature working manacle. There was similar sympathy for the dignity and plight of Native Americans. The ordinarily pedestrian West Point drawing instructor Seth Eastman looks more like Brueghel in his charmingly energetic painting of lacrosse on ice, Ballplay of the Dakota on the Saint Peters River in Winter (1848). Charles Wimar, perhaps the most talented of a whole school of mid-century specialists in Native American genre scenes, painted Indians Crossing the Upper Missouri (1859-1860) in the Technicolor style he acquired at the Düsseldorf Academy; sunset irradiates the placid water and surrounding buttes with a light that is as apocalyptic as it is romantic, both a tribute to and a prophecy for a people already regarded as doomed.

Despite its checkered past, the Carter’s West never loses its mythic power. The West as a crucible of American modernism is a theme the museum has made its own, with a stunning collection of abstract landscapes by artistic pilgrims to New Mexico in the twenties and early thirties: Stuart Davis, Arthur Dove, Marsden Hartley, John Marin, and the doyenne of them all, Georgia O’Keeffe, who actually first essayed the West while teaching school in Canyon; her watercolor-on-newsprint Light Coming on the Plains, No. 1 (1917) depicts the sunrise in echoing, arcing strokes of blue-green wash. Robert Adams, the dean of contemporary Western photographers, whose work is the subject of the largest of the opening photography shows (on view through January 27), revisited the Western landscape in three separate series dating from the late sixties. Beginning with White Churches of the Plains, austere, reverent views of late-nineteenth- and early-twentieth-century clapboard churches in Colorado, Adams progressed to ironic documentation of diners, convenience stores, tract houses, and graffiti at historic sites; in the nineties he regained his faith with a series of light-flooded, almost vaporized seascapes, shot in the mouth of the Columbia River, that seem to recapture the transcendental yearnings with which we began our Western quest, in another century on another coast.

Long a key player in the new history of the Old West, the expanded Carter will assume an even more prominent role as a destination for advanced study. “We’ve built a Ph.D.-level research facility,” says Stewart, himself a leading Western-art scholar, pointing to basement rooms full of drawer after drawer of prints and negatives and row after row of meticulously filed documents, destined to be catalogued on the museum’s Web site. And while it plans to organize some splashy loan shows, like next fall’s “Celebrating America: Masterworks From Texas Collections,” the Carter will make bigger waves with smaller “focus” exhibits mined from its own vaults, exploring such themes as Hartley’s and Strand’s artistically intriguing road trip to Mexico in the thirties as well as such big and contentious issues of contemporary Western scholarship as race and the environment.

The net result of all the Carter’s basement musings promises to be anything but esoteric. To wander through the new Amon Carter Museum is to take a thrilling roller-coaster ride through the American psyche, from Cole’s representation of our original innocence to Remington’s embodiment of our jingoistic self-confidence, from Ward’s and Wimar’s tragic self-recognition to Hartley’s and O’Keeffe’s search for a new century’s new vision and Robert Adams’ metaphoric struggle for redemption. It is the story of us, our nation’s great collective epic, told as never before in all its subtle colors and dramatic shades of light and dark.