Almost half the country, according to a Gallup poll last month, worries a great deal about the quality of the environment. An additional third worry a fair amount. And why wouldn’t people worry? It seems that almost every day a new concern about climate change or the health effects of pollution emerges.

But with Earth Day just this last Saturday, it’s important to remember the environment is actually getting better by many measures.

Federal regulations are one side of this story — atmospheric lead levels plunged once appropriate action was taken — but they’re not the whole story. State and local efforts along with natural market forces have powered huge environmental gains.

The Association of Air Pollution Control Agencies represents 40 state and local air agencies and senior officials from 20 state environmental agencies. It released a report this month detailing “the greatest story seldom told.” The story is that of the environmental success the United States has seen over the past several decades.

One of the most striking findings in the report shows that from 1970 to 2015, six common air pollutants the EPA regulates have fallen by 71 percent. But it gets even better. These gains have not come at the cost of modern conveniences. Appliances and cars today use less energy to do the same jobs, so we now are able to do more with less. The six pollutants have declined even as national gross domestic product and the number of vehicle miles driven have soared.

Though federal regulations certainly play a part, state and local groups are also striving to improve the environment. The AACPA is itself evidence of the success of cooperative federalism and thus of empowering local groups over federal bureaucrats.

Cooperative federalism models work because they don’t rely on all-knowing and benevolent bureaucrats in faraway places. Instead, local officials are much better positioned to understand local conditions and limitations. Because cooperative federalism capitalizes on the ability to experiment with many different models among the states, other states can then copy those that have been successful elsewhere. In fact, while most individuals report not being completely satisfied with national environmental quality, another Gallup poll found most people are satisfied with their local environmental quality.

Of course, there are still important challenges. Salt Lake City routinely ranks among the worst air quality in the nation. But we shouldn’t allow the propensity to focus on the negative to cloud our view of the improving picture as a whole. The gains made by state and local efforts should serve as evidence of the potential for continued improvements, even for areas like Salt Lake that still face air quality challenges.

One final piece of good news for the Earth is the decoupling of carbon-dioxide emissions and economic growth. Even though only a few years ago it would have been thought impossible, Brookings Institution scholars have documented how robust, but low-carbon economic growth has been powered primarily by advances in fracking technology. One of the best recent changes for slowing climate change has been the shift from coal to natural gas, as natural gas produces about half as much carbon dioxide per unit of energy generated.

The fascinating story behind the fracking revolution is how it was driven almost purely by market forces. Technological innovations suddenly made natural gas a better option than coal both by economic and environmental measures. These kinds of improvements are happening all the time and they’re powered by simple economic theory. People demand higher environmental quality as their incomes rise.

The environmental Kuznets curve depicts the empirical relationship between income and common pollutants and emissions. It shows that as income rises, environmental measures first decline, but after a certain level of wealth is attained, the relationship reverses and income grows as environmental measures improve. The trend is an upside down U shape and not a constant decline in environmental quality. This is because after people meet their basic needs, they then begin to want to improve the environment they live in and finally have the resources to make that happen.

Environmental challenges for future generations remain unsolved, but it’s hopeful to see the many and vast improvements made. Policymakers, especially those in Washington, should remember the powerful potential in granting state and local groups the necessary authority to make their own changes. Plus, we should all inject a little Earth optimism into our lives.