On Earth Day, 1971, a nonprofit called Keep America Beautiful launched TV ads to persuade people to stop littering.

If you grew up watching Saturday morning cartoons in the '70s, you'll remember them.

Each one featured an American Indian paddling or riding or walking through a trashy landscape and a grave voice over, ending with "People start polution. People can stop it." At the end of each ad, the camera zooms in on the Indian's face, onto a single tear.

The crying Indian got America to stop littering.

That ad is the one I remember most.

Do watch it. Then forgive me a guess about what you're thinking: Powerful TV, but really.

Of course, the '70s were top-down times. One example: Elvis Presley, master of media, had three TVs built into the wall of this basement at Graceland. Three televisions were all he needed to watch everything shown on TV in America. There were only three channels, so The King was set.

The Indian in the ads was a career actor named Iron Eyes Cody. He became known as The Crying Indian -- better known for those ads than for any other role in in his career, which began when he was 12. While Iron Eyes lived his life as an Indian, Wikipedia says he was born Italian-American, from Louisiana.

And there are all sorts of conspiratorial accusations against Keep America Beautiful. The organization purportedly got its funding from corporations and fast-food vendors. Wouldn't it be better, the accusers say, to encourage people to buy less styrofoam than to clean up litter?

Yet the ads inspired genuine feeling. And people did (mostly) stop littering. A mark of their power today: their YouTube comments are mostly positive.

What's the Crying Indian for our time? And, post-network-TV, what's the medium? The net, surely -- but which net? A thousand blogs? Twitter? Facebook? YouTube? (And do all the brand names in that list creep anybody out, is it just me?)

I want to know what kind of campaign it would take to stop pollution -- really stop it.

People start pollution. People can stop it.

But how?