This article is part of a series exploring how the Americans With Disabilities Act has shaped modern life for people with disabilities.

The Capitol Crawl, it came to be called. In March 1990, several dozen activists, cheered on by supporters, left their canes and wheelchairs and pulled themselves up the steep stone steps of the United States Capitol.

They wanted to pressure Congress into ratifying the Americans With Disabilities Act. At the heart of what became a landmark of civil rights legislation was the elemental role of architecture and design — literally building accessibility into cities, products, public spaces and workplaces, without which equity would remain just talk. Business leaders predicted doomsday costs if the A.D.A. passed. The New York Times even published an editorial titled “Blank Check for the Disabled?

Thirty years on, the A.D.A. has reshaped American architecture and the way designers and the public have come to think about civil rights and the built world. We take for granted the ubiquity of entry ramps, Braille signage, push buttons at front doors, lever handles in lieu of doorknobs, widened public toilets, and warning tiles on street corners and subway platforms. New courthouses, schools and museums no longer default to a flight of stairs out front to express their elevated ideals. The A.D.A. has baked a more egalitarian aesthetic of forms and spaces into the civic DNA.

But there’s still a long way to go.

Last fall, the 22,000-square-foot, $41.5 million Hunters Point branch library opened in Queens, N.Y. With a soaring interior of vertiginous tiers and zigzagging stairs, the project’s architectural ambition was obvious and outsized. My review called it one of the most uplifting public buildings New York had produced in years.

Disability rights advocates saw it differently. All those stairs and tiers made certain areas inaccessible to people in wheelchairs, they pointed out. How uplifting could a public library be if some people — who expected, deserved and needed to use it — felt unwelcome?

Credit…Hiroko Masuike/The New York Times

They were right. I was wrong. City officials insisted that the building complied with A.D.A. regulations, in effect pointing the finger at the law itself. As Karen Braitmayer, a Seattle architect and accessibility consultant, put it, “that’s very definitely neither the spirit nor the goal” of the legislation.

The question I wish I’d asked at the time is one that architects and designers might ask themselves more often today. Bess Williamson, author of “Accessible America,” tweeted it when the library opened: “Who sets the priorities?”

A public building has everyone as its client, after all. Does its design evolve out of a truly collaborative process that engages, upfront, the diversity of users, including those with disabilities, who know best what they need and want?

“There is only so much that legislation can ever do,” Xian Horn, a disability rights advocate, speaker and teacher in New York, born with cerebral palsy, said recently. “The issue goes beyond civil rights. It’s also about hospitality, patronage, a broader vision of accessibility, and ultimately about doing what’s best for the bottom line.”

With one in four American adults living with disabilities, designing for accessibility and diversity should hardly be considered a chore or just a compliance issue. It’s an opportunity, both economic and creative, but one that requires a shift in mind-set. A ramp can be something stuck onto a building to check off some legal requirement.

Or it can inspire the helical design of the Ed Roberts Campus in Berkeley, Calif., by Leddy Maytum Stacy Architects. Or the serpentine pathways of the Robert W. Wilson Overlook that Weiss/Manfredi, the New York architecture firm, recently devised to wind through the Brooklyn Botanic Garden.

“Architecture, from Vitruvius through Le Corbusier, has mirrored Western culture, for whom the default user has always been the straight, white, healthy, tall male,” said Joel Sanders, a New York-based architect and Yale professor who runs MIXdesign, a think tank focused on inclusion. “Everyone else, including those with mobility or cognitive issues, tends to become an afterthought, a constraint to creativity, an added cost.”

Nearly a century ago, tubular steel inspired both Marcel Breuer’s Wassily chair and new, lighter wheelchairs. Chairs by Charles and Ray Eames, now classics of midcentury modernism, evolved from a molded plywood splint the couple devised for wounded soldiers during World War II.

“The most beautiful things we design,” as Mr. Sanders put it, “are often the ones whose formal innovation is the product of a social or cultural need.”

Credit…Steven Severinghaus, via Brooklyn Botanic Garden

A couple of years ago, the Cooper Hewitt, Smithsonian Design Museum organized an eye-opening show called “Access+Ability” highlighting those sorts of designs. It included stylish puffer jackets with Velcro seams and zip-on sleeves, sold by Target, the retail giant, and a pair of FlyEase, designed by Nike in response to a letter from a college-bound teenager with cerebral palsy who asked for sneakers that didn’t look like medical equipment. The sneakers looked fantastic.

A term of art emerged during the 1960s and ’70s: universal design.

Today, “universal design” can sound a little reductive and creaky, with its implication of a single norm, as if difference (physical, cognitive, racial, gender, religious, age, you name it) boils down to a condition that needs to be compensated for — as if it can’t be something worth celebrating. There’s a debate today in the Deaf community about cochlear implants, for example, because to some detractors the implants imply that deafness is a problem to be solved, not a culture and condition with its own history and pride.

“Noncompliant bodies don’t need to be ‘made whole’ by designers,” as Mr. Sanders told me.

He prefers the term “inclusive design.”

Call it what you will, examples include text to speech and the homely curb cut — that little ramp carved into street corners so wheelchair users can navigate the six or so vertical inches between pavement and sidewalk. Mandated by the A.D.A., during the last three decades the curb cut has made daily life easier for countless shoppers with grocery carts, teenagers on skateboards, travelers pulling wheeled bags, parents with strollers and just about everybody else.

“As a person with a mobility disability who grew into adulthood prior to the passage of the A.D.A.,” recalled Ms. Braitmayer, the architect and consultant, “I spent my early years in a community without curb cuts on the street corners, without accessible parking at the neighborhood retail shopping centers, without wheelchair spaces in the movie theaters. I appreciate every time I can now go to a movie and find a place to sit without being told that if I sit in the aisle in my wheelchair, I would be a fire hazard.”

But for architects and designers, abiding by the letter of the A.D.A. isn’t the same as internalizing its civil rights goals, she said. That is what still remains for architecture — “to lift itself into the next realm,” was Ms. Braitmayer’s phrase.

“People don’t only buy Apple products because they’re functional,” added Ms. Horn, the advocate and teacher. “If you make a phone or a building or a park or a hotel beautiful and also accessible, it makes life better for everyone.”