American Woman: Fashioning a National Identity opens Wednesday at the Metropolitan Museum’s Costume Institute and provides a peek at the way a tiny swatch of well-to-do society gals, all mostly dressed in French finery, shaped the image of women in this country. At least that’s what the curator of the Costume Institute, Andrew Bolton, said he wanted to do with this magnificent collection of clothing, mostly from the Brooklyn Museum’s vast costume collection. Bolton has organized the exhibit around six American “identities”—the heiress, the Gibson Girl, the bohemian, the suffragette and the patriot, the flapper, and the screen siren. But there is a major omission here, and I don’t know if it has to do with money—the working-class gal, the one who has fought for her place in the social strata rather than marry into it. It’s a shame because she, perhaps more than any archetype in the show, has influenced the way we dress today.

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There is still a lot to learn from this show. The clothes themselves look impeccable, probably because they haven’t seen the light of day in 30 years, but also because they are displayed in a series of oval rooms inspired by the pavilions at the 1893 Chicago World’s Fair. The visual design of the show is also beautifully conceived. The designer, Nathan Crowley, sets the mood for each archetype with hand-painted backdrops. The studios of Louis Comfort Tiffany inspire the bohemian room, Tamara de Lempicka-type cubist paintings serve as a backdrop to the footloose beaded flapper dresses, and the Astors’ Newport mansion, Beechwood, is the setting for heiresses decked out in grand French ball gowns by Charles Frederick. And it also is worth noting the wigs, which were designed by the French stylist Julien d’Ys and which made me realize how important hair is in America (but that’s another show, and one that would definitely have to include mannequins of color).

Initially Bolton’s idea was to use the Brooklyn Museum collection to illustrate the influence of American style icons—socialites you’ve probably never heard of like Rita Lydig, Mona Bismarck, and Consuelo Vanderbilt. But on further examination he realized that these clothes also could be organized around archetypes as they appeared in the mass media from 1890 until 1940.

Where are the working-class female archetypes? They helped shape the style of American women as much as the swell set.

“All of these characteristics are part of American style,” explained Bolton, a dapper Brit in horn-rimmed glasses. They include the heiress who was most vividly depicted in Henry James’ novels and the robber-baron daughters who married European aristos and hung out in mansions in Newport, Rhode Island. Out of this pastoral idyll emerged the athletic and independent minded Gibson Girl (actually, she emerged from the pen and ink drawings in Life magazine of Charles Dana Gibson, the very well-connected artist who spent most of his time sketching ladies of leisure at play). Next up was the bohemian of the late 1890s who decided to take on a bit of intellectual baggage and begin thinking about more important issues like sexual and political freedom. They ditched their corsets and embraced the comfy caftans of Paul Poiret and the Callot Soeurs—the four Parisian sisters who stitched up exotic gowns in lace and lamé. As time went on, the American woman liberated herself not just from corsets but also from the shackles of a male-dominated society. This brings us to the flapper, the suffragette, and, finally, that über-American icon: the screen siren.

The strongest vignette is undoubtedly the one of the Gibson Girls. It’s fascinating to see how far our wardrobes have come from the days when cotton sailor tops and matching culottes were considered “bathing suits.” By contrast, the somber ermine-tipped riding jackets and skirts from Frederick Loeser & Co. look surprisingly modern, like something Yohji Yamamoto might send down the runway in Paris. Connoisseurs of vintage costume will get a kick out of the screen siren section, where quite a few dresses, including Charles James’ “lobster” dress, serve as rare examples of true design innovation. A much-needed dose of reality comes crashing through all of this noble scenery in the gallery devoted to the suffragist movement, where larger-than-life blowups of footage from the WPA film library depict patriots at work during World War I and suffragettes marching in 1910. It’s probably the only glimpse of the industrious and rebellious spirit that defines the true American woman.

Standing in that particular room watching these angry suffragists on the march—as if out of the pages of a newspaper—one wonders where the real American woman is in all of this. Where are the strong, daring, independent women who represent the healthy American spirit—the same spirit we see today in self-defined post-feminist icons like Michelle Obama and Hillary Clinton? The exhibit ends in 1940, which is a shame because most of the political and social emancipation of women has taken place in the last 50 years, and the questions those changes raise about fashion and the way we present ourselves are still the most compelling issues facing designers today.

I understand that much of the thesis was driven by the contents of the Brooklyn Museum’s collection, but where are Hillary and Michelle’s ancestors? Presumably we will not find them in the Beechwood Mansion or the Louis Comfort Tiffany studio. Where are the gritty, daring, hardscrabble pioneers who worked in the fields, for example, or drove their wagons west, migrated north from the South after emancipation, swilled whiskey in the saloon, or marched off to work in the factories with Rosie the Riveter? Where are the working-class female archetypes? They helped shape the style of American women as much as the swell set. Is their style contribution any less significant than that of the Callot Soeurs or forgotten American dressmakers like Elizabeth Hayes and Jessie Franklin Turner? True, the plainspoken style of the American working class was perhaps not sumptuous or dramatic enough to make it museum worthy, but the practicality and functionality of those clothes made them influential and as quintessentially American as a pair of Gap jeans.

Much of the history of this country is the history of money—hence the heiresses—but what is overlooked in this exhibit is the industry of ready-made fashion that boomed in the early part of the 20th century and made it possible for a larger population to wear stylish hats, gloves, and shoes. These were factory-made clothes that changed the way Americans felt about themselves. They were clothes that gave disenfranchised Americans, the sons and daughters of European immigrants and African-American slaves, a sense of belonging and possibility. Even Vogue magazine offered up guidance for the “alert, efficient, responsible business girl” with its “department of smart fashions for limited incomes,” which it launched in 1923.

The real backbone of American fashion is the utilitarian, functional, practical look that emerged out of the working class. Mass-market utilitarian clothes like T-shirts and jeans are the archetypes of American fashion and they still inspire the way we dress today. The freedom and confidence they inspire is not rooted in the elitist pomp of the “penny princesses.” Denim, after all, did not make its debut in the Astors’ Newport mansion.

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Kate Betts is a contributing editor at Time magazine and until this year was also the editor of Time Style & Design, a special supplement to the magazine. Previously, Betts was the editor in chief of Harper's Bazaar and the fashion news director of Vogue. She is the author of the book Everyday Icon: Michelle Obama and the Power of Style , due out February 2011.