I remember the first time I saw them. I was in the Library of Congress, looking through old issues of High Times magazine. The advertisements for certain products—like the BuzzBee Frisbee (with a special pipe so you could literally “puff, puff, pass”), “You’re the Dealer!” board game, and pictures of clowns hawking rolling papers—seemed both charmingly representative of the mid-1970s as well as pretty blatant in their appeal to kids. The ads also spoke to the enormous paraphernalia market that had risen as a result of a dozen states decriminalizing the possession of up to an ounce of marijuana between 1973 and 1978. The numerous ads that lined the pages of High Times (as well as the existence of the magazine itself) give some insight into just how vast the marketplace, and its clientele, was at the time.

That booming paraphernalia market, however, would also prove to be decriminalization’s undoing. By 1978, rates of adolescent marijuana use had skyrocketed, with 1 in 9 high school seniors smoking pot every day and children as young as 13 reporting that the drug was “easy to get.” This angered a growing number of parents, who saw kid-oriented paraphernalia as a “gateway” to drug use. The grassroots parent movement, which began in 1976 and came to its height of influence during the Reagan administration, worked to overturn state decriminalization laws and reaffirm the federal government’s anti-marijuana stance. Once decriminalization was overturned, the paraphernalia companies that had sprouted across the country folded as quickly as they had formed.

This previous experiment with decriminalization shows exactly how shaky the current legalization efforts in the United States might actually be. Despite widespread support for legalization (including from all current 2020 candidates for the presidential Democratic nomination), an unregulated and hyper-commercialized marijuana marketplace was unpopular enough to overturn lenient drug laws 40 years ago, and could potentially do so again today.

The rise of the paraphernalia marketplace of the 1970s was grounded in two truths: America’s increasing interest in recreational marijuana use, and a struggling economy that searched for any opportunity for growth. During a period of “stagflation” and long gas lines, cannabis created its own thriving industry, from people whittling wooden pipes in their garages to major companies importing incense and beaded curtains from India. These legal products (used to enjoy a still-illegal substance) were freely available, in places like head shops, record stores, even 7-Elevens. They also sold extremely well: by 1977, paraphernalia was bringing in $250 million annually. (That amounts to over a billion dollars today.)

Still, no regulations dictated what these products should look like, what they sold, or which demographics could be targeted in their ads. A 1978 New York Times article found that three children, aged 11 to 13, were able to purchase $300 worth of paraphernalia with no questions asked. Paraphernalia’s often blatant appeal to kids became the decriminalization movement’s undoing because it was easy for parent activists to draw a line between a spaceship-shaped bong and rising rates of adolescent marijuana use.

Something distinctly different is going on today. In most of the 10 states that have legalized recreational marijuana use, clear regulations seek to prevent cannabis products, at least edible products, from appealing to kids. In California, edibles can’t look like regular candies or baked goods, and in Colorado, edibles can’t be shaped like “humans, animals, fruit or cartoons.” The potency of individual servings has limits, and nearly all states require products to come in “child-resistant” packaging (though what qualifies as “resistant” varies). As an additional measure, most states also require the “universal symbol” (a diamond with an exclamation point and the letters “THC”) on all cannabis products, notifying users they’ve purchased an intoxicant.

In some ways, this new wave of restrictions should be a relief, especially to parents. Legislators seem to have actually learned something from the past; after all, if appealing to kids killed the decriminalization movement of the 1970s, banning kid-oriented products should help preserve the current era of legalization. By prohibiting the sale of legal cannabis to anyone under 21 and barring the production of cartoony edibles, legalized states are doing something right.

But the past is also coming back to haunt the cannabis industry, with a thriving new economy surrounding the drug and paraphernalia market that seems to have been pulled straight from old issues of High Times. Customers can buy golf tees that serve double duty as pipes. There’s a belt buckle that holds a one-hitter. And marijuana board games have returned, including Lords of Cannabis and Zonk.

Where cannabis itself is legal, a new wave of products containing pot is cresting. Customers can buy everything from cannabis-infused chocolate bars and truffles to sodas, breath mints, and beauty products. The new legal market also means that these goods can be purchased at dispensaries in Las Vegas that are open 24 hours a day, seven days a week, or at drive-throughs in Colorado.

Unless you’re a parent worried about the safety of your child, many of these products probably seem as silly today as they did in the 1970s.

Still, some lessons from the past would be useful for today’s cannabis legislators and marketers to remember. Forty years ago, marijuana seemed like a sure bet. Decriminalization, many assumed, would lead quickly to legalization, since paraphernalia sales showed that there was money to be made, and a clientele ready and willing to support the market.

Today, a similar belief in legalization’s inevitability exists. Beyond arguments for the benefits of medical marijuana and the social justice value of curtailing racist arrests, the potential profit for marijuana has only increased. The “green rush” that propelled paraphernalia into a $250 million industry in 1977 has evolved into a legal cannabis marketplace expected to generate $39.4 billion by 2023.

As a historian, however, I am suspicious of the definite path supporters say legalization will take. After all, few expected that, in just a few years, angry parents would overturn every decriminalization law in the 1980s. And though public approval for legalization is high today, the drug is still illegal in 40 states, and remains a Schedule I substance at the federal level.

This means that legalization’s future is far from certain, and it’s a reminder that the market itself should self-police. Despite regulations over age of sales and edibles packaging, the cannabis marketplace is once again booming. It was spaceship-shaped bongs that turned Americans against decriminalization 40 years ago; between recent efforts to regulate teens’ use of e-cigarettes like Juul to mounting fears of the threat posed by Big Marijuana, there’s no telling what might turn people against legalization today.

A blatant rush to profit today, similar to the paraphernalia market of the 1970s, could overturn the progress made by countless legalization activists over the past 20 years. Unless the market chooses to self-regulate, another graduate student might be at the Library of Congress in 40 years, wondering at how quickly and easily America’s brief experiment with legalization was overturned.

This article originally appeared on the American Historical Association’s newsmagazine Perspectives.

Emily Dufton is the author of Grass Roots: The Rise and Fall and Rise of Marijuana in America (Basic Books). She received her PhD in American studies from George Washington University. You can follow her on Twitter @emily_dufton.

Established by the AHA in 2002, the National History Center brings historians into conversations with policymakers and other leaders to stress the importance of historical perspectives in public decision-making. Today’s author recently participated in the NHC’s Washington History Seminar program.