Niagara Falls, the most famous waterfall in North America, was on the brink of destruction less than a century after the US was born. By the 1860s, this incredible natural wonder, located on the border of New York state and Canada, had been given over almost entirely to energy interests.

The French writer and historian Alexis de Tocqueville urged a friend in 1831 to visit the falls before it was too late: ?If you delay, your Niagara will have been spoiled for you,? he said.

Soon after Tocqueville?s warning, American painter George Catlin called for ?a nation?s park? to be preserved ?by some great protecting policy of government?. Catlin had travelled out West to paint portraits and scenes from daily Native American life and feared that modern westward expansion could result in catastrophe for Native tribes and their surrounding wilderness.

Many Americans who travelled West were especially struck by the reverence of the Yosemite Valley. Frederick Law Olmsted, the architect who designed New York City?s Central Park, called Yosemite ?the greatest glory of nature?. Eventually, Californians convinced one of their representatives, Senator John Conness, to translate rhetoric to action. In May 1864, Conness introduced legislation to bring Yosemite Valley and the Mariposa Grove of Giant Sequoias under the control of the state of California. President Abraham Lincoln signed the bill into law.

Yosemite was established upon the simple yet ground-breaking idea that wilderness should be preserved from commercial interests for the sustainable use and enjoyment of all people. A decade after Yosemite became a state park, the world?s first national park was decreed when a group of scientists led by geologist Ferdinand Hayden determined that the geothermal springs in the Yellowstone area of the Wyoming Territory must be saved.

Upon Hayden?s urging, Congress and President Ulysses S Grant founded Yellowstone National Park. It was the country?s first step toward creating an official system of national parks. US naturalist John Muir, the founder of the Sierra Club, was also an early and effectrive advocate in the public land movement. Muir fought to protect Yosemite and later Glacier Bay in Alaska, Mount Rainier in Washington and the Grand Canyon and the Petrified Forest in Arizona.

America?s ?best idea,? as writer and historian Wallace Stegner called the national parks, went on to spur the creation of protected parkland throughout the world.

Around the same time activists in America were fighting to protect Yosemite and Yellowstone, environmentalists in Australia sought to defend the beautiful lands of Tasmania. Although in 1863 Tasmanian reserves were set aside for ?scenic purposes?, it wasn?t until 1879 that Australia established its first, and the world?s second, federally protected park — now known as Royal National Park.

Canada followed in 1885, founding its first national park in the Rocky Mountains, now Banff National Park. Then came New Zealand with Tongariro National Park in 1887, protecting the Tongariro, Ngauruhoe and Ruapehu volcanoes. Europe began its park system with a collection of parks in Sweden in 1909, while Africa?s first national park was the Democratic Republic of Congo?s Virunga National Park, founded in 1925 to protect the gorillas of the Virunga Mountains, and Asia?s first was Hailey National Park, now Jim Corbett National Park, also created as a wildlife sanctuary, in 1936.

There are now more than 4,000 national parks around the globe, according to the International Union for Conservation of Nature. In the US, more than 270 million people visit the national parks system each year.

Even the more tormented parts of the world are beginning to experience the egalitarian beauty of public wilderness. In 2009, Afghanistan declared Band-e-Amir, a collection of six mineral-rich, piercingly blue lakes, a national park in hopes of protecting and promoting its landscape. According to BBC News, thousands of people visit this unique wonder even though tourism has all but halted in the violence-plagued country.

As more and more people get the opportunity to experience public lands, these precious places increasingly face certain challenges that come with tourism ? including overdevelopment, commercialization and pollution. Yet documentarian Ken Burns, who together with Dayton Duncan produced the series The National Parks: America?s Best Idea, argued that this is a much more desirable scenario than the alternative: the very exploitation that came so close to spoiling the grandeur of Niagara Falls.

Thanks to the parks movement, Niagara has enjoyed public protection since the 1880s when it became a state park, and just four years ago, the US designated Niagara Falls a heritage area under the National Park Service.