This week, Senator Cory Booker introduced legislation to legalize marijuana nationwide. If passed, New Jersey’s Democrats' bill would “expunge federal marijuana convictions and penalize states with racially-disparate arrest or incarceration rates for marijuana-related crimes,” according to The Washington Post.

Thing is, the drug wasn’t always prohibited. Anglo-Americans and Europeans have known about marijuana’s medicinal benefits since at least the 1830s. Around that time, Sir William Brooke O’Shaughnessy, an Irish doctor studying in India, documented that cannabis extracts could ease cholera symptoms like stomach pain and vomiting. By the late 19th century, Americans and Europeans could buy cannabis extracts in pharmacies and doctors’ offices to help with stomach aches, migraines, inflammation, insomnia, and other ailments.

Just because people in the past used something for medicinal purposes doesn’t always mean it was a good idea. But modern research has backed up claims that marijuana has real medical benefits. For example, it can decrease seizures and alleviate pain without causing physical dependence.

Despite its medical usefulness, many Americans’ attitudes toward cannabis shifted at the turn of the century. This was at least partly motivated by Mexican immigration to the U.S. around the time of the 1910 Mexican Revolution, according to Eric Schlosser, author of Reefer Madness: Sex, Drugs, and Cheap Labor in the American Black Market.

“The prejudices and fears that greeted these peasant immigrants also extended to their traditional means of intoxication: smoking marijuana,” Schlosser wrote for The Atlantic in 1994. “Police officers in Texas claimed that marijuana incited violent crimes, aroused a ‘lust for blood,’ and gave its users ‘superhuman strength.’ Rumors spread that Mexicans were distributing this ‘killer weed’ to unsuspecting American schoolchildren.”

It’s worth noting that research has shown alcohol to be more dangerous than marijuana. In addition, cannabis doesn’t really cause superhuman strength, and the U.S. Drug Enforcement Administration’s fact sheet on the drug says that “No death from an overdose of marijuana has been reported.”

Even though there was no evidence to support claims that marijuana had a Jekyll-and-Hyde effect, 29 states outlawed marijuana between 1916 and 1931. The Marihuana Tax Act of 1937 essentially banned it nationwide despite objections from the American Medical Association related to medical usage. This act came just a year after the film Reefer Madness warned parents that drug dealers would invite their teenagers to jazz parties and get them hooked on “reefer.”

The federal government and states continued to increase punishments related to marijuana until the late 1960s when the laws began to touch white, upper-middle-class college students who were smoking the drug.

“During the mid-1970s, virtually all states softened penalties for marijuana possession,” reports The New York Times. However, the federal government continued to cling, as it does today, “to a policy that has its origins in racism and xenophobia and whose principal effect has been to ruin the lives of generations of people.”

Today, 29 states and Washington, D.C., have legalized medical marijuana, and 8 states plus D.C. have legalized it for recreational use. Its illegality at the national level has created tension between the federal and state governments. However, growing consensus around the issue suggests that legalization—or rather, re-legalization—could be in America’s future.