Georgia O’Keefe at Prospect Mountain, in Lake George, in 1927. Photograph by Alfred Stieglitz / National Gallery of Art, Washington, Alfred Stieglitz Collection

On June 20, 1966, Jane Jacobs was speaking out against the destruction of Washington Square Park. “SOS, Park Association of New York City Opposes N.Y.U. Library!” reads the sign taped to the table. And another: “N.Y.U. Don’t block off the … ” The signs overlap. The light? The street? The park? All of the above.

Jacobs was protesting New York University’s plans to build a library on the south side of Washington Square, a great red hulk that she and fellow-protesters feared would turn the public park into an academic green and loom over low-rise row houses. “All the glamour of Philip Johnson [the project’s architect] won’t save that corner of the park from gloom,” she said. “The two elements most destructive of urban parks are highways and educational institutions.” She’d already stopped Robert Moses’s proposed throughway a decade before; now she was trying to take care of the second element.

Peering at a blotchy black-and-white image of this historic event, I noticed something distinctive about the hem of Jacobs’s dress: a lighter-colored scallop wending its way around the bottom, like the brick border on a garden plot. The Jane Jacobs look was simple to the point of caricature: blunt bob with bangs, thick black eyeglass frames, beads. A skirt fit for cycling around Manhattan. Where had I seen that border before? Then it came to me: at the Brooklyn Museum’s current exhibition “Georgia O’Keeffe: Living Modern,” a deeper-than-you-might-think look at the painter’s curation of her wardrobe, home, and image. Against one wall, the curator Wanda M. Corn lines up a series of O’Keeffe’s long-sleeved, full-skirted cotton dresses from a Finnish company that epitomized modern fashion: Marimekko. O’Keeffe and Jacobs had (almost) the same dress.

Maybe this is a footnote, but it is a fascinating one. In 1963, the same year that O’Keeffe probably bought her dress, Eugenia Sheppard, the fashion critic for the New York Herald Tribune, called such dresses “a uniform for intellectuals . . . Marimekko is for women whose way of wearing clothes is to forget what they have on.” Who could be more desirous of forgetting what they had on than women such as Jacobs and O’Keeffe, who had so much to do? And who would better understand their needs—skirts for riding, pockets for paper and pen—than powerhouses such as Annika Rimala, who designed their dress and its textile, and Armi Ratia, who founded Marimekko, in 1951, intent on bringing back Finnish industry after the war.

Marimekko was made for the working woman who could afford to ungirdle herself, one in a long line of “reform-dress” movements that started with the nineteenth-century feminist bloomer. These dresses are the opposite of the tailored and belted and solid-color sheaths worn as a kind of female armor by Julia Louis-Dreyfus’s Selina Meyer on “Veep”—and by the Trump women. They aren’t feminine interpretations of the suit-as-uniform but dissent from the idea of sucking it in and putting on a show. O’Keeffe had read Charlotte Perkins Gilman, an early twentieth-century feminist who wrote on both women’s dress and women’s rooms. Wearing such clothes went along with living in a modern way, and O’Keeffe also bought Saarinen chairs and Arabia pottery from Finland for her desert home.

Marimekko likewise has urbanist bona-fides. Its dresses first came to America, in 1959, via the store Design Research, founded by the architect Benjamin Thompson. Thompson spotted the textiles at the 1958 Brussels World’s Fair, where the young female exhibition guides wore the company’s wares as an “anti-uniform.” He first sold them out of his store on Brattle Street, in Cambridge, Massachusetts, but, in 1963, D/R (as it was commonly known) opened a new store in a tall, narrow town house on Fifty-seventh Street in New York, and hung multistory Marimekko banners out the windows. There’s no direct proof that that’s where either woman bought her dresses, but the timing and location fit: O’Keeffe noted D/R’s address in her appointment book, and her scallop-hem “Varjo” dress dates to that year.

The modernist strip on Fifty-seventh Street was a handful of blocks from Jacobs’s old office at Architectural Forum, and she was well aware of Thompson and his work: in a 1981 talk, titled “Can Big Plans Solve the Problem of Renewal?,” she cites a few new plans as “food for imagination,” including Faneuil Hall and Quincy Market, in Boston, designed by Benjamin Thompson and Associates; and Ghirardelli Square, in San Francisco, where a third D/R store opened, in 1965. These mixed-use developments, adapting old industrial buildings to shops, homes, and offices, were, as she said in that talk, “fresh ideas” and “aberrations” that “flout the accepted way of doing things.” So were the Marimekko dresses, which freed the body. In Rimala’s view, “clothes needed to be designed so that it was possible to move freely in them—to run, jump, and sit,” or, for that matter, to protest.

Marimekko is, and was, known for its wild patterns and unorthodox color combinations —how often do you see orange and pink side by side?—but O’Keeffe selected the drabbest ones: a black-and-brown striped “Mother’s Coat” dress, in a fabric and style adapted from Marimekko’s popular “Jokapoika” shirts for men; a black-and-gray floral; a black-and-green wide stripe; and the black-and-gray “Varjo.” Most of these dresses had loose long sleeves, big pockets, and triangular silhouettes.

As the Brooklyn Museum exhibition makes clear, long before social media O’Keeffe knew her best angles and her best outfits—she sewed a number of them herself—engineering a public image of scintillating consistency. Her edit of Marimekko speaks to her critical eye, for O’Keeffe wore these dresses around the house, as everyday wear, and only for photo shoots on those occasions where the assignment called for something casual. Life magazine’s John Loengard, for example, captured her grooming her dogs in Marimekko. Tony Vaccaro, another of O’Keeffe’s favored photographers, whose work is featured at the Brooklyn Museum, was behind the camera for a 1966 Life story, “Bright Spirit of Marimekko,” which included the rainbow hues that O’Keeffe eschewed.

One of the salesladies at the Fifty-seventh Street D/R store was a woman named Berthe Rudofsky, who “knew everyone” from the designer Charles Eames to the kinetic sculptor Yves Tanguy via her husband, the architect Bernard Rudofsky. In 1944, Bernard Rudofsky curated an influential exhibition at the Museum of Modern Art called “Are Clothes Modern?” that explored, among other themes, the painting of skin, the binding of flesh, and the sculpting of hair through the ages and across cultures. In terms of women’s dress, the exhibit came down firmly on the side of freedom. “The more helpless a woman, the more attractive she is supposed to be to man. To keep her from moving freely, he hampers her walk with anklets, stilts, hobble skirts and heels,” read the wall text. To find a solution, Rudofsky recruited the designer Claire McCardell to create stylish garments made from large rectangles of cloth: unlike the wardrobe fitted to the body, and ruled by etiquette, these clothes could be inexpensively made, folded and rolled for storage, and reused for other garments. As he saw it, “they would end our artificial categories (white tie, black tie, afternoon, etc.)” and make us again “aware of the inherent beauty of uncut materials.”

O’Keeffe also owned a number of McCardell dresses. McCardell’s clothes for the market, rather than the museum, were already roomy, simple, and designed for activity, ranging from playsuits to denim, with big pockets, wide skirts, and wrapped tops. Her models wore flats. Newspapers called it the “American look.” O’Keeffe’s McCardells, which have full skirts and belts, and little bows at the neck, were purchased from department stores such as Saks Fifth Avenue and Bergdorf Goodman. They are more formal to our eye than Marimekko’s paper-doll shapes, but aimed for the same modern woman a decade earlier. If O’Keeffe liked a dress she had it copied, making her own intellectual’s uniform before she could buy the Marimekkos.