If it's Earth Day, it must be the time of year for volunteers to turn out en masse to plant trees. Those events certainly were prominent across the U.S. on Sunday, but they were not the only ones.

Among them: a "Mobilize the Earth" rally and concert on the National Mall -- and 100,000 condoms (wrapped with covers of endangered species) were being handed out by an environmental group as part of its population control campaign.

In Washington, D.C., Cheap Trick, British rocker Dave Mason and teen pop group Kicking Daisies performed at a rain-dampened rally sponsored by the Earth Day Network.

The organization is urging people worldwide to perform one billion "acts of green". 

EDN President Katherine Rogers said those acts have included commitments to walk to work, plant trees and hold environmental education programs in schools across the globe.

"My favorite was a guy who broke up with his girlfriend because she wouldn't recycle -- we counted that as an act of green," the Associated Press quoted Rogers as saying.

Also on the mall, university students were competing in the 8th annual National Sustainable Design Expo, which is hosted by the Environmental Protection Agency.

And an "EcoVillage" featured interactive exhibits and renewable energy demonstrations from exhibitors including NASA and the United Nations.

Tens of thousands crowded the mall two years ago to hear Sting, Jimmy Cliff and other musicians play on the 40th anniversary of the first Earth Day. The event wasn't held last year because Earth Day fell on the same weekend as Easter and Passover and because of the economic downturn, Rogers said.

Jacquelyn Martin / AP

In a steady rain storm, Anastasia Bardin, 10, and her mother Lyn Bardin of New York City join the Earth Day rally on the National Mall in Washington Sunday.

As for the condoms, the Center for Biological Diversity handed those out this week to 1,200 volunteers to distribute at more than 80 college campuses.

"What better day than Earth Day to get people talking about overpopulation and its environmental impacts," Amy Harwood, who runs the group's population campaign, said in a statement. "The world population has doubled since the first Earth Day 42 years ago, and yet today that rarely gets talked about. But the fact is that we add 80 million people to the planet each year, leading to pollution, habitat destruction, and the prospect of extinction for thousands of species already living on the brink."

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Jim Pickerell / AP

In this January 1973 photo released by the U.S. National Archives, trash and old tires litter the shore at the middle branch of the Patapsco River in the harbor of Baltimore, Md.

Patrick Semansky / AP

And now...

WASHINGTON -- A polluted drainage ditch that once flowed with industrial waste from Lake Charles, La., petrochemical plants teems with overgrown, wild plants today.

A light-rail line zips past the spot where a now-defunct Portland, Ore., gasoline station advertised in 1972 that it had run out of gas.

A smoking Jersey City, N.J., dump piled with twisted, rusty metal has disappeared, along with the twin towers of the World Trade Center in lower Manhattan that were its backdrop.

Photographers revisit sites of EPA's Documerica project to see how things have changed over 40 years

Forty years after the Environmental Protection Agency sent an army of nearly 100 photographers across the country to capture images at the dawn of environmental regulation, The Associated Press went back for Earth Day this year to see how things have changed. It is something the agency never got to do because the Documerica program, as it was called, died in 1978, the victim of budget cuts.

AP photographers returned to more than a dozen of those locations in recent weeks, from Portland to Cleveland and Corpus Christi, Texas. Of the 20,000 photos in the archive, the AP selected those that focused on environmental issues, rather than the more general shots of everyday life in the 1970s.

Gone are the many obvious signs of pollution — clouds of smoke billowing from industrial chimneys, raw sewage flowing into rivers, garbage strewn over beaches and roadsides — that heightened environmental awareness in the 1970s, and led to the first Earth Day and the EPA's creation in 1970. Such environmental consciousness caused Congress to pass almost unanimously some of the country's bedrock environmental laws in the years that followed.

Today's pollution problems aren't as easy to see or to photograph. Some in industry and politics question whether environmental regulation has gone too far and whether the risks are worth addressing, given their costs.

Republican presidential contender Mitt Romney has called for the firing of EPA chief Lisa Jackson, while GOP rival Newt Gingrich has said the EPA should be replaced altogether. Jackson has faced tough questioning on Capitol Hill so often the in past two years that a top Republican quipped that she needs her own parking spot.

"To a certain extent, we are a victim of our own success," said William Ruckelshaus, who headed the EPA when it came into existence under Republican President Richard Nixon and was in charge during the Documerica project. "Right now, EPA is under sharp criticism partially because it is not as obvious to people that pollution problems exist and that we need to deal with them."

Environmental laws that passed Congress so easily in Ruckelshaus' day are now at the center of a partisan dispute between Republicans and Democrats. Dozens of bills have been introduced to limit environmental protections that critics say will lead to job losses and economic harm, and there are those who question what the vast majority of scientists accept — that the burning of fossil fuels is causing global warming.

In the 1970s, the first environmental regulations were just starting to take effect, with widespread support. Now, according to some officials in the oil and gas and electric utility industries, which are responsible for the bulk of emissions and would bear the greatest costs, the EPA has gone overboard with rules.

For instance, Documerica photographers captured a wave of coal-fired power plants under construction. Republicans and the industry now say environmental regulations are partly to blame for shuttering some of the oldest and dirtiest coal plants.

Jim DiPeso of ConservAmerica, a group that recently changed its name from Republicans for Environmental Protection, says the EPA is caught in the center of a perfect storm. "This time of greater cynicism about government, more economic anxiety and the fact that the problems are not immediately apparent, has created this political problem for EPA," he said.

In an interview, Jackson said she believes that people in the United States still want to protect the environment. "There's a large gulf between the rhetoric inside the Beltway to do everything from cut back on EPA to get rid of the whole place, and what the American people would actually stand for," she said. "It's very easy to make rash statements without thinking about what that means to the health of everyday Americans."

A 2010 Pew Research Center survey showed that 57 percent of those questioned held a favorable view of the EPA, compared with a 1997 poll that showed 69 percent with a positive view of the agency. A CNN/Opinion Research Corp. poll taken last year found that 71 percent of people surveyed said that the government should continue provide money to the EPA to enforce regulations to address global warming and other environmental issues.

"We are not done. We still have challenges we have to face," Jackson said.

The agency last year began a volunteer photography project called State of the Environment. More than 620 people have participated and submitted 1,800 photographs, but only a few are at the same sites at the 1970s project.

Images always have spurred environmental consciousness. A 1980s satellite picture of the ozone hole helped lead to a ban on the chemicals in aerosol cans and refrigerants that were responsible. Underwater video of oil spewing into the Gulf of Mexico in 2010 opened the public's eyes to the gravity of the largest offshore oil spill in U.S. history.

But a second Documerica project, with professional photographers, would be impossible today, given budget cuts facing the agency and the wariness of industry barring access by photographers.

Lyntha Scott Eiler, 65, shot photographs for Documerica around her then-home in northern Arizona, as well as one of the early emissions testing sites for automobile exhaust in Hamilton County, Ohio. At the Navajo Generating Station in Arizona, Eiler got right down in a strip mine "where the shovels were."

"They weren't afraid of the EPA, so it was, 'What else you do you want to get a photograph of?,'" Eiler said. "You probably would have a hard time doing that today."

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