Born 35 years ago in a fever of political activism, Earth Day is now a Hallmark Holiday. Earth Day and its traditional pieties about recycling and conservation now engender all of the public passion of Arbor Day.

The Hallmarkization of Earth Day aptly symbolizes the predicament of 21st century ideological environmentalism. Unfortunately for green activists, the public now recognizes that their relentless predictions of imminent environmental apocalypse are a bunch of hooey.

In fact, people need only look around to see that the state of the natural world in the United States and much of the world has greatly improved over the past 35 years. Sure, public schools still teach environmental doomster tracts to impressionable children, but public schools are always decades behind the rest of society, being, after all, the absolutely last places where new facts and ideas infiltrate.

Just in time for Earth Day, the American Enterprise Institute and the Pacific Research Institute released their annual Index of Leading Environmental Indicators 2005. The 2005 Index looks at trends in air and water quality, the amount of toxic materials being released into the environment, and forest growth in the United States. Some the best news is on air quality trends. The Index finds that "air pollution fell again in the United States to its lowest level ever recorded." The Environmental Protection Agency (EPA) reports that since 1976, when national measuring began, levels of ozone in the air have dropped 31 percent, sulfur dioxides are down 72 percent, nitrogen dioxide was cut by 42 percent, carbon dioxide plunged 76 percent, and particulates (smoke and dust) fell by 31 percent. Air quality in the 10 largest metropolitan areas (four of the five most improved are in California) has improved an average of 53 percent since 1980.

The long-term trend in toxics being released into the environment is also positive, dropping by 55 percent since 1988. Despite ongoing suburbanization, between 1990 and 2000, U.S. forests expanded by more than 10 million acres. The Index notes that "for the eastern half of the United States, land cleared for farming and grazing in the 19th century has been reverting back to forestland at a net rate of one million acres a year since 1910." A big part of the reason that forests are expanding is that we no longer use horses for transport (land cleared for their grazing) and wood for fuel. Annual use of wood for noncommercial fuel has fallen from 5 billion cubic feet in 1900 to about 500 million cubic feet.

More problematic are water quality trends. Not because they are getting worse, but because scientists have never devised a good system for tracking water quality trends in rivers and lakes. The problem is that droughts, floods, seasonality and many other variables affect water quality in any given body of water at any given point. The EPA, trying to remedy this data insufficiency, has launched the Wadeable Streams Assessment program which will monitor streams at 500 randomly selected locations.

Nevertheless, Lake Erie is no longer "dead;" the Potomac, which in the 1960s was lined with signs warning against coming into contact with the water, now has beavers swimming under the Key Bridge connecting Roslyn and Georgetown; and the Cuyahoga River, which infamously caught fire, is now an upscale riverfront dining and entertainment district. The Index points out that the United States has spent nearly a $1 trillion on water quality since 1970. As a result, the wastes from 165 million Americans are today treated at modern sewage plants, up from 86 million in 1968.

One possible negative trend is that fish consumption advisories, largely due to rising concerns about mercury contamination, have been increasing over the past few years. This is a bit odd considering that U.S. mercury emissions declined by 45 percent between 1990 and 1999. The Index authors attribute the jump in fish advisories not to increased levels of mercury pollution, but rather to greater bureaucratic efforts to detect mercury contamination. In any case, the hypercautious EPA in 2004 observed, "For most people, the risk from mercury by eating fish and shellfish is not a health concern."

Most of the positive environmental trends identified in the Index for the United States are mirrored by similar trends in other rich developed nations.

These improvements in environmental quality are the result of a combination of increasing economic efficiency and, yes, some heavy-handed government regulations. During a panel discussion held at AEI on the occasion of the release of the Index, AEI scholar Roger Bate highlighted the point that wealth creation and the institutions that underpin wealth creation (property rights, rule of law, democratic governance) precede environmental clean up. Policies that slow down economic growth also slow down eventual environmental improvement.

Sadly, not all environmental trends are positive. For example, both in the United States and globally, wild fisheries are being overharvested. Reducing water pollution from nonpoint sources is still problematic. Corrupt governments in poor countries continue to sell off their nation's forests without regard to the desires of local people. And supplies of fresh water are being overstressed in many places around the world. In general, where environmental degradation continues, you will find that the resource is unowned and thus unprotected.

Despite these remaining problems, we have enjoyed a solid record of environmental recovery over past 35 years. So instead of taking to the streets to agitate, most Americans will simply celebrate the 35th Earth Day by breathing clean air, drinking clean water, and enjoying the increasingly clean environment around them.