Lower Manhattan remains in the vanguard of the green revolution. We’re not just planning it, we’re living it.

But much has changed since the first Earth Day, back on April 22, 1970.  These days, no one talks about ecology the way they did back then. Today the word is green. The Hudson River is clean, aerosol cans are history (to my Aunt Harriette’s consternation) and New York City is creating parks and promenades for pedestrians where just a few years ago there was only asphalt. PlaNYC has replaced the Whole Earth Catalog as the manifesto of what we now call sustainability. And bikes are out of the playgrounds and into the streets and bike paths.

I was almost 10 on the evening of April 21, 1970, when 1,000 people gathered at the intersection of Wall and Broad streets to hear Jacob Javits and Pete Seeger herald the marriage of progressive politics and environmentalism. The next day, more than 100,000 New Yorkers—including my father and I—marched down Fifth Avenue to Union Square, where Mayor Lindsay and others called for a cleanup of the polluted Hudson River, no more smog, and fewer cars. Odetta sang We Shall Overcome and a movement was born.

Environmentalists have changed the way we live, and it shows in Lower Manhattan. With 308,000 workers and 55,000 residents in one square mile, Downtown defines sustainability; it is a scalable community on a human scale. Ninety percent of employees take public transportation or walk to work— and restaurants, shopping, schools and attractions are all within walking distance.

That’s what makes Lower Manhattan a neighborhood, green in every sense of the word.  We have more green buildings.  That means built or renovated to the standards of the US Green Buildings Council for Leadership in Energy and Environmental Design (LEED), or the equivalent, and includes the Port Authority’s One World Trade Center, Silverstein Properties’ Seven World Trade Center (the first New York City office building to receive LEED gold status) and more than five million square feet of sustainable residential and commercial construction in Battery Park City.

We have more new parks, open or under construction, than any other part of the city—Hudson River Park, East River Waterfront Park, Battery Park, Wall Street Park, Titanic Park and the playground at Burling Slip—and plans for more, including the transformation of Edgar Plaza proposed in the Downtown Alliance’s Five Principles for Greenwich South and endorsed by Community Board 1.

Now as then, Earth Day champions collective and individual responsibility. It’s about the big picture, but it’s also about what each of us can do every day to make Lower Manhattan, New York City and the planet better.  The lesson of Earth Day is that everyone can make a difference (like throwing Aunt Harriette’s spray cans in the garbage).

With this in mind, I hope you will bring your friends, kids and neighbors to join me in Wall Street Park (between South and Water streets on Wall) on Saturday, May 1 between 10 am and 1 pm for the Downtown Alliance’s Community Planting Day.  We’ll supply the plants, tools and refreshments, and the opportunity to work together to make Downtown even greener.

—Liz Berger is President of the Downtown Alliance