[Above—A two-hour wait: Tourists queue in drizzle for the cable car up Mt. Huangshan, China, a World Heritage site. Annual visitation c.4 million.  Photo: Jonathan Tourtellot]

Celebrated on Sept. 27, World Tourism Day is an observance championed by the U.N. World Tourism Organization and intended to point out the value of tourism. Initiated 35 years ago, much of the impetus for World Tourism Day sprang from the desire to convince governments and industry that tourism was bigger and more important than they realized. This is understandable, because tourism is bigger and more important than almost anyone realizes. When tourism works well, it’s fun and beneficial. It boosts the economy, helps preserve cultural and natural sites, and educates the public. When it doesn’t…well, that’s the dark cloud inside the silver lining.

This year’s theme was “One billion tourists—one billion opportunities!” Nice and upbeat, but it smacks of the more-is-better boosterism led for years by an officialdom that calls for ever-increasing numbers of arrivals.

This attitude is naïvely out of date. Better to think more realistically of “One billion tourists—two billion footprints.” Tourism, counted among the very largest industries on Earth, is changing the face of the planet and posing challenges with its relentless growth.

Of all the famous malaprops attributed to the late, beloved Yogi Berra, none rings truer in the tourist world than: “Nobody goes there anymore. It’s too crowded.”

Over the past half century, international travel has increased almost 20-fold in terms of arrivals. Domestic tourism worldwide has kept pace, at four or five times the volume. Growth continues unabated, but the places all these people visit are still the same size. Resorts and vacation homes gobble up coastlines. You can see the press of numbers most clearly in the world’s great cultural sites, from Venice to Angkor to Chichén Itzá.

Early this year, I was privileged to visit Argentina’s Perito Moreno glacier, famed for steadily calving into an Andean lake. It’s in Los Glaciares National Park, a World Heritage site. It lies far, far south in Patagonia, down toward the end of the inhabited world, 1700 miles (2700 km) south of Buenos Aires. In short, not a place you’re likely to visit on the way to some other region. Yet annual visitation ranks in the hundreds of thousands, with over 600,000 people moving through the airport at the booming gateway town of El Calafate.

If we now see that much tourist traffic about as far as you can get from the human population’s center of gravity, it’s no wonder more accessible, better-known destinations are drowning in it. Florence, for example, must cope with 16 million tourists a year, many of them day-trippers who clog the streets while contributing little to the quality of the city.

World Tourism Day should now carry an additional mission. Not just: “It’s big! It’s great!” But also: “We will learn how to manage it better!” We need deeper, more meaningful and memorable travel experiences and fewer busloads armed with selfie sticks.

Another one of Yogi’s sayings was “If you come to a fork in the road, take it.” That impossible ambiguity fits tourism leaders who maintain: Quantity, quality, can’t we have both?

In most cases—no, you can’t.