The country’s media infrastructure has undergone periodic confluences of technological, political, and social changes—what historians sometimes call “critical junctures.” These moments create rare windows of opportunity for activist interventions and radical ideas. By crystallizing a social contract between commercial media institutions, government, and the public, policy decisions at these junctures can profoundly shape our information system’s trajectory.

One such inflection point occurred in the 1940s during policy battles over radio, which resulted in America’s preeminent medium being largely captured—and some would say degraded—by commercial forces. With the public airwaves marred by excessive advertising and low-quality programming, many felt that radio’s revolutionary promise was being squandered to over-commercialization. This growing anger was experienced most acutely among African Americans, labor unions, and intellectuals who felt excluded and powerless as commercial media neglected or misrepresented their voices and viewpoints. To advance their politics they needed to change the system, and to do so they needed to change media policy.

A spirited media-reform coalition of activists and average listeners entered policy debates and targeted the Federal Communications Commission with letters and petitions.

One letter from a returning World War II veteran noted that racist radio programming like the popular Amos ‘n’ Andy evidenced an “American Fascism.” Many decried radio’s anti-labor slant. Pleading that “labor and capital both be heard equally,” one representative letter asked that radio not be “utilized so exclusively for sheer advertising and propaganda purposes.” A self-described housewife urged the FCC, “Please keep up the fight. If it means government control, better that than [advertiser] control.” These letters certainly did not represent all or even most listeners, but they gave voice to a palpable disgust with what had become of American radio.

This surge in criticism and engagement with policy—what Fortune dubbed “The Revolt Against Radio”—coincided with a rare progressive bloc at the FCC. Even as the New Deal project was in various stages of retreat elsewhere, a social democratic vision arrived later and stayed longer at the FCC. The liberal faction was led by two southerners, FCC chairman Larry Fly from Texas, and the commissioner Clifford Durr from Alabama. To defend democracy and the public interest they aggressively went after commercial broadcasters. Bolstered by grassroots pressures, the FCC launched a number of progressive initiatives throughout the decade aimed at reining in the power of media monopolies and defining public service responsibilities for broadcasters. These policy interventions resulted in forcing NBC to divest itself of one of its two networks (which is how ABC was formed), mandating that broadcast license renewals be dependent on meaningful public interest obligations (the FCC’s infamous “Blue Book”), and establishing the much maligned and misunderstood Fairness Doctrine (which was actually a consolation prize in the fight for stronger regulations).