Between the first and last decades of the 20th century, visionary leaders from both parties—often working with an engaged corporate elite—crafted America’s distinctive and remarkably successful “mixed economy” of public and private initiative. These leaders recognized that private businesses, for all their vital contributions to prosperity, frequently failed to protect health and safety or make the long-term investments in public goods necessary for sustained growth. They recognized that private businesses sometimes produced public “bads”—dangerous and deceptive products, polluted air and water, distorted and captured polices—if doing so would also produce profits. As much as they saw competitive markets as essential, they believed that the strong thumb of government needed to assist and counterbalance the nimble fingers of the market (as the political economist Charles Lindblom would later describe this mixed model). The meteoric improvements in health, education, and living standards that defined “the American century” did not just happen. They were made possible by energetic government.

Reducing the toll of lead was a crucial, if belated, part of this transformation. In the middle of the 20th century, lead in gas and paint were a hidden poison that undermined the potential of millions of Americans. At the time, most American children were routinely exposed to lead levels far higher than those in Flint. Then as now, the worst affected were disproportionately poor and black, because levels were so dangerously high in the congested streets and aging buildings of inner cities.

Fortunately, the scientific community fostered by America’s mixed economy conclusively demonstrated lead’s catastrophic impact on developing brains. This knowledge came along with heightened awareness of the need for the robust use of public authority to combat this threat: from regulations on lead in gasoline and paint to the regular monitoring of toxic chemicals in soil and water. Starting in the 1970s, a bipartisan coalition that included Republican presidents Nixon and Ford rapidly increased the capacity of government to address these challenges. The federal government forged the path, overcoming powerful lobbies defending business as usual. Over corporate opposition, the EPA began steps to phase out lead in gasoline in 1973. Over corporate opposition, the Consumer Product Safety Commission banned lead paint in 1978. Efforts to remove lead from existing buildings and soil intensified. For 40 years, federal, state and local governments worked in tandem to get lead out of the water, air, and soil.

Such quiet efforts typically attract little fanfare. But they had a revolutionary impact on public health. The Center for Disease Control estimates that almost 90 percent of American children aged 1-5 had lead levels above 10 micrograms per deciliter in the late 1970s. Today, less than 1 percent do. The improvements were greatest for poor and minority children (who had by far the highest rates to begin with). This decline translates into markedly higher IQs, increased economic potential, and, quite likely, considerably lower rates of crime and teenage pregnancy. (Lead poisoning reduces impulse control as well as cognitive functioning). It feels callous to reduce the protection of young brains to an economic calculation, but the economic benefits have surely been staggering: By one careful estimate, they add up to $260 billion per year.