The motivation behind ratifying the 18th Amendment on January 16, 1919 was clear: Alcohol was a corruptive, corrosive lubricant, and America would be better off without it.

On the 100th anniversary of this societal shift, it’s worth noting that Prohibition had another, lesser-known consequence: It opened the door for hate groups to gain a greater foothold in America.

Making the sale and transportation of alcohol illegal was supposed to contribute to a strengthened moral fiber in the 1920s. But the sentiment behind it had roots in racism. "The Klan felt immigrants and anyone not of WASP (White Anglo-Saxon Protestant) heritage was the underlying cause of America’s problems," according to Tennessee's Museum Center at 5ive Points. They argued that immigrants from Europe were importing their drinking habits and contributing to a relaxed social standard that organizations like the Woman's Christian Temperance Union and the Anti-Saloon League dubbed a “saloon culture.” Before long, they reasoned, the U.S. would be overrun by Catholic foreigners contributing to societal decay. Bootleggers couldn’t be arrested fast enough.

That’s where the Ku Klux Klan stepped in. The organization was originally founded in 1866 to resist the Reconstruction period of a post-Civil War America. When their sentiments were drowned out by support for civil change, their numbers dwindled before being revived in the 20th century. As part of a sort of recruitment strategy, the Klan began mixing their message of discrimination against minorities with support for Prohibition. Advocacy for clean living was intermingled with the idea that immigrants were responsible for the hedonism associated with alcohol and so many of America's other wrongs.

In communities around the country, Klan representatives succeeded in creating concern by insisting that Catholics, Jewish community members, African-Americans, Hispanic people, and immigrants were feeding the continued disregard for the law. Rather than blanket towns with unfiltered hate speech, they convinced residents that minorities were responsible for illegal alcohol trafficking, speakeasies, and flagrant disobedience of the ban.

The Klan then took it a step further, convincing Prohibition supporters that they could pick up the slack left by overworked police who were struggling to stop bootleggers from flourishing. Evangelical Americans, stirred by fear over the Klan’s depiction of a bad element taking over the country, began to support their cause. If people were in favor of Prohibition, then it only made sense to be anti-immigration, too. The Klan even found federal support for its ambitions, supplying foot soldiers in attacks on Italian alcohol barons in Herrin, Illinois in 1923. Violence and planted evidence were common complaints among those targeted.

Any raids the Klan performed on bootleggers were rarely about seizing alcohol—and if they did, they typically drank it themselves. Instead, it was an excuse to terrorize Catholic neighborhoods in a display of power. Such groups, the Klan argued, were violating Prohibition and had to be stopped. As a result, Klan factions—including some for women and children—sprung up across the country. If supporters weren’t inherently racist, then they could get behind the blanket message to enforce the law.

Either way, Klan numbers grew, with an estimated 2 to 5 million members pledging their commitment to the cause between 1920 and 1925. The erupting violence during raids eroded those numbers in some communities, as people finally caught on that harassment of immigrants—not the betterment of America—was the Klan's primary goal.

The Klan’s ability to piggyback on Prohibition was lost in 1933, when the 18th Amendment was repealed by the 21st Amendment. The group wouldn’t be seen as a formidable force again until the rise of the civil rights movement. But for a good portion of the 1920s, they were able to grow in strength and numbers based on the promise of moral upkeep. The “noble experiment” of banning alcohol, which was intended to curb salacious behavior, would forever be associated with the malevolent intentions of the Klan.