President Trump wants more “patriotic” American history curriculums. He’s not the first to try. Americans have long been anxious over what schools teach, and this has produced fierce ideological battles over what fills textbooks.

Many Americans believe students directly absorb whatever is written in their textbooks. That makes the stakes over what gets into these books on science, health or history immensely high — an entire generation of Americans stands to be indoctrinated. That perspective, at least, has been the sense of conservative activists in Texas, who for decades have campaigned for more “patriotic” books to ensure the next generation of voters receive, as they see it, the right message.

Since the late 1960s, these activists have become increasingly adept at shaping the character of school history texts. Because of the size of Texas’ textbook market, their activism influenced what was taught to all American children. For publishers, it was not economically viable to write one book to appease campaigners in Texas and a different version to sell elsewhere. The result: Students across the country got books that told U.S. history from the perspective of a small group of White, God-fearing, conservative Texans. Over 20 years, textbook activists shifted the meaning of “patriotic history” from a postwar liberal consensus to a right-wing, colorblind, heteronormative, nationalist retelling of the American story — one that persists today.

For as long as there have been history textbooks, there have been activists trying to change them. Since the landmark 1954 Supreme Court decision in Brown v. Board of Education, which found segregated schooling unconstitutional, conservatives have most vociferously and successfully campaigned for their version of history in textbooks. The accomplishments of the civil rights movement threatened all the social certainties that conservatives held dear. Alongside their resistance to desegregation, conservative activists seized upon the history curriculum because it allowed them a way to control the narrative of the changes America was undergoing.

By the 1970s, the turbulent history of the past two decades had to be included in the textbooks. In Texas, conservative activists transformed their approach, shifting focus from critiquing already-written textbooks toward a wholesale takeover of the bidding and selection process. Most significantly, they targeted the content guidelines, a set of basic instructions given to publishers upon which to base their books.

These guidelines had never been overtly left wing. They had always called for books to be “patriotic” in character. Indeed, with titles such as “The Glorious Republic” or “Land of Promise,” and with covers adorned with bald eagles and fluttering stars and stripes, there was no mistaking them for anti-government propaganda. But the definition of patriotism on which they were based reflected a bipartisan, postwar consensus of liberal internationalism.

As late as 1977, for example, the content guidelines counseled: “Textbook content shall promote citizenship and understanding of the free enterprise system, to emphasize patriotism and respect for recognized authority, and to promote respect for human rights.” Moreover, changing gender roles and the increasing participation in society by minority groups were to be accommodated alongside “traditional” understandings of the family and the Founding Fathers.

For conservatives, these guidelines were too liberal to meet the challenge of writing about the damage done to their White, patriarchal, nonthreatening American ideal during the 1960s. While they leaned right, these frames risked exposing students to the revolutionary potential of organized movements for racial equality, which threatened to further dismantle the structures of White supremacy. They also promised to uncritically acknowledge “un-American” monsters like communism, gender equality or LGBT rights. Such stories posed a threat to capitalism’s ideological dominance and the notion of the nuclear family around which it was structured.

By 1979, conservative activists, via newsletters, books and national press coverage, had successfully pressured the State Board of Education and the 15-member committee (which may well have agreed with them anyway) into making changes. Into the guidelines went an amendment counseling: “Textbooks shall present positive aspects of America and its heritage; they shall not contain material which serves to undermine authority; the amount of violent content should be limited; content shall not present lifestyles deviating from generally accepted standards of society.”

These new guidelines posed a challenge for textbook authors. How, for example, could one tell a history of the civil rights movement that didn’t portray the undermining of established power structures? Or one in which there was limited violence? More widely, what exactly constituted the “generally accepted standards of society?”

Publishers had to quickly settle on a solution. The violent history of struggle and change in the United States could not simply be ignored to appease new-right ideologues. It could, however, be recast in language that neither offended them, nor celebrated what they saw as “unpatriotic” stories of campaigns for racial, sexual and social equality.

The result was a heroic “vanilla” history of America. An American story in which the exceptionalism of the American creed met whatever challenges came its way, solved them and continued triumphantly onward. It was a history in which cause and effect were nullified, state violence removed and the kidnapping of humans from Africa labeled “immigration.”

Martin Luther King Jr.’s exhortation that all be judged on “the content of their character,” for example, chimed nicely with a colorblind conservative narrative that neatly folded civil rights struggle into a wider story of progress. Such oratory was celebrated, while the beating of civil rights protesters and King’s ideological socialism were downplayed. The more militant Malcolm X was included, but only so he could be shown to have been assassinated. The message was clear: In this version of the United States, protesting was unpatriotic, and it would get you killed. And those citizens, galvanized by racial inequality, who took to the streets in the late 1960s in protests and uprisings against recognized authority were cast as having simply destroyed their own neighborhoods in an act of wanton destruction. Patriotism, it seemed, had come to mean easy answers.

Liberal groups such as People for the American Way were aghast at what was happening in Texas. They launched counter campaigns in the early 1970s to try to break conservative activists’ stranglehold on the textbook selection process, to no avail. Liberal appeals to critical thinking, multiculturalism and social history failed to capture the imaginations of the decision-makers as successfully as the conservatives’ fire-and-brimstone rhetoric, which presented “unpatriotic history” as a threat to the nation’s soul.

As the 1980s wore on, the clamor at the state level spilled into national discourse. In 1983, the Reagan administration published “A Nation at Risk,” which decried the “dumbing down” of the nation’s textbooks and the problems this posed for younger Americans trying to compete in a rapidly globalizing workforce. By the early 1990s, many books about what America should be teaching its children became bestsellers, and a national commission convened to define once and for all a set of national standards for the history curriculum. But conservative pundits decried the outcome for the same reason conservatives had demanded change in Texas: They saw the guidelines as promoting an unpatriotic version of America.

Meanwhile, in Austin, conservative activists continued attending the public hearings on textbook content and lobbying hard for their version of the past. To this day, by crusading against what they see as dangerous ideas, they continue to influence what children all over America are taught. National discourse over exactly what history should be carries on, but the most effective change has always happened at the grass-roots level — where local officials are more receptive to demands that curriculums reflect the values of their communities.

Trump’s pledge to create a commission to promote patriotic history should be understood within this longer history of textbook activism. It is designed to promote a sunny, uncritical vision of the past that the president’s base has been demanding, with much success, for decades, even as historians point out flaws in these politically infused narratives.