The curb cut（路缘坡）is a convenience that most of us rarely, if ever, notice. Yet, without it, daily life might be a lot harder—in more ways than one.

Pushing a baby stroller onto the curb, skateboarding onto a sidewalk or taking a full grocery cart from the sidewalk to your car—all these tasks are easier because of the curb cut.

But it was created with a different purpose in mind.

It's hard to imagine today, but back in the 1970s, most sidewalks in the United States ended with a sharp drop-off. That was a big deal for people in wheelchairs because there were no ramps（斜坡）to help them move along city blocks without assistance. According to one disability rights leader, a six-inch curb "might as well have been Mount Everest" for wheelchair-bound people. So, activists from Berkeley, California, who also needed wheelchairs, organized a campaign to create tiny ramps at intersections to help disadvantaged people dependent on wheels move up and down curbs independently.

I think about the "curb cut effect" a lot when working on issues around health equality. The first time I even heard about the curb cut was in a 2017 Stanford Social Innovation Review piece by PolicyLink CEO Angela Blackwell. Blackwell rightly noted that many people see equality as "a zero-sum game（零和游戏）". Basically, there is a deeply rooted social belief among them that intentionally supporting one group hurts another. What the curb cut effect reveals though, Blackwell said is that "when society-creates the circumstances that allow those who have been left behind to participate and contribute fully, everyone wins."

One such example is closed captioning（字幕）, originally intended to help deaf people understand movies and TV shows without needing to hear dialogue or sounds. But it's easy to think of other applications for closed captioning: it's convenient for customers watching TV in a noisy bar or gym, second-language learners who want to read as well as listen, or students who use it as a study aid.

So, next time you cross the street, or roll your suitcase through a crosswalk or ride your bike directly onto a sidewalk—think about how much the curb cut, that change in design that broke down walls of exclusion for one group of people at a disadvantage, has helped not just that group, but all of us.