On April 22nd in 1970, thousands of people gathered in New York City's Union Square Park for the world’s first Earth Day celebration. Those of us organizing events in cities all across the country were excited about the promise of environmentalism - not only as an effort to curb pollution and save the planet’s natural habitats and wildlife, but also as a powerful citizen’s movement.

In preparation, we convinced Mayor John Lindsay to shut down Fifth Avenue from Midtown to 14th Street, and to close off 14th Street and Union Square. Closed to vehicle traffic, these urban thoroughfares transformed into lively pedestrian avenues as well as stages for street theater and peaceful protest.

The mood that day was energetic and triumphant. Here we were—students, workers, activists of all stripes—together and full of hope, fighting for change in some of the city’s most historic public spaces and streets. Still, there was a heaviness looming over the event: the war was still raging in Vietnam, and rumors of its expansion into Cambodia were becoming more and more real (in only a few days, this anger would reach a tragic peak with the fatal protests at Kent State). Despite the sun and celebration, this was also a sweeping protest, and environmental activism often went hand in hand with the anti-war, civil rights, and student movements of the time.

We’ve made great strides since that first Earth Day—our air is less polluted, we’ve cleaned up toxic dumpsites, and we’ve overseen the passing of all kinds of environmental legislation—but today’s cities face some even greater challenges. While addressing environmental degradation, we also need to confront the increased inequity within our cities; we need think creatively and together about alleviating traffic congestion and unplanned sprawl; and we need to find ways to address growing health disparities and uneven access to public spaces and social resources.

We need a broader movement that can speak to all of these issues—one that can speak to and for every community. In some very exciting ways, the environmentalist movement of the 20th century has given way to a more localized focus on sustainable urban Placemaking in the 21st century.

Placemaking is both a philosophy and a process that works to strengthen the connection between people and the places they share. I was wary at first, when people began to refer to Placemaking as the “new environmentalism” (I’m more concerned with the process and results, rather than any kind of label or re-established “ism”). But the term does make some sense if we expand our usual definition of “environment” to include those places we call home—our streets, neighborhoods, communities—the places where our lives unfold every day.

The practice of Placemaking is of course not new, though until recently it’s been a relatively quiet movement. For decades, it has taken shape around citizen-led activism and thousands of grassroots efforts. More recently, in places like Detroit, public and private stakeholders have joined together to effect full-on re-animations of neighborhoods, downtowns, and sometimes even entire cities.

As the movement enters the mainstream, it is essential that every sector of society participates in it. And we need leaders at all levels—from community organizers to CEOs. The funding support we are now seeing for Placemaking shows that foundations and even large corporations are joining the cause, and recognizing the vital role public spaces play in our cities and communities.

Today, nearly half a century after that spring day in Union Square, the desire for transformative change is as strong as ever—though it has taken a new shape.

Let’s continue to do everything we can to address climate change and to protect our vast and troubled wildernesses—but let’s remember that this is just one aspect of saving the Earth. Let’s also work to make streets safer, encouraging people to walk and bike more and to drive less. Let’s continue lobbying for accessible and enjoyable public spaces, and for public markets that provide communities with healthy affordable food. Let’s stop building wide streets and sprawling parking lots that exacerbate pollution and global warming. Let’s turn impersonal and outdated strip malls into neighborhood centers that include mixed-income housing, public squares, sidewalk cafes, and convenient transit stops.

The Placemaking movement has emerged as a way to bring environmentalism back home. We all care deeply about the places where we live, and there’s nothing more inspiring than being able to see, and indeed be a part of, immediate change.