About a century ago, millions of Americans feared that members of a religious group were amassing an arsenal of weapons for a secret, preplanned takeover of the United States.

The feared religious group was not Muslims. It was, as the Los Angeles Times's Matt Pearce wrote in a great new piece on Wednesday, Catholics:

Hatred had become big business in southwestern Missouri, and its name was the Menace, a weekly anti-Catholic newspaper whose headlines screamed to readers around the nation about predatory priests, women enslaved in convents and a dangerous Roman Catholic plot to take over America.… America's deep and widespread skepticism of Catholics is a faint memory in today's post-Sept. 11 world. But as some conservative politicians call for limits on Muslim immigration and raise questions about whether Muslims are more loyal to Islamic law than American law, the story of Aurora's long-ago newspaper is a reminder of a long history of American religious intolerance. Today, there are calls for federal surveillance of mosques in the name of preventing terrorist attacks; a century ago, it was state laws that allowed the warrantless search of convents and churches in search of supposedly trapped women and purported secret Catholic weapons caches.

This may seem absurd today, but there was a real fear among Protestant Americans back then that Catholics were planning to take over the country. As Pearce reported, the fears led to serious violence: Lynch mobs killed Catholic Italians, arsonists burned down Catholic churches, and there were anti-Catholic riots. It was a similar sentiment to the kind of Islamophobia today that's led many Americans to call for shutting down mosques, forcing Muslims to register in a national database, and even banning Islam.

The point of the comparison is not to say that the US faces the same problems today as it did a century ago, or that the discrimination toward Catholics back then and Muslims today is exactly the same. But when looking back at the history of the US, it's easy to see a pattern of consistent xenophobia and fears of outsiders.

Xenophobia makes a regular appearance in US history

In response to terrorist attacks in Paris and San Bernardino, much of the conversation has focused on refugees and immigration. This conversation has been tinged with xenophobia toward Muslims — with many Republican presidential candidates going as far as saying the US should ban Muslim refugees, people from Muslim-dominated countries, or Muslims altogether.

But this sort of rhetoric is not new to the US. As the Pew Research Center found, Americans have generally opposed taking in refugees even as they went through abhorrent, well-known crises. (Vox's Dara Lind noted that America even rejected some Jewish refugees fleeing Nazi Germany.)

Xenophobia has fueled other policies, too. In the late 19th century, the US passed the Chinese Exclusion Act to stop the flow of Chinese laborers into the US. During World War II, the US put Japanese Americans in internment camps after the country declared war on Japan. Throughout the war on drugs, lawmakers have regularly tapped into xenophobic sentiments to prohibit certain drugs — such as when San Francisco banned opium smoking that was perceived as popular among Chinese immigrants, and when prohibitionists built up opposition to marijuana by fearmongering about its use among Mexican immigrants.

Throughout all of these periods and policies, the public and lawmakers cited genuine policy interests: national security, keeping American laborers competitive in the job market, and preventing drug abuse. But underlying such policy stances were obvious signs that Americans were simply scared of foreigners who weren't like them.

By and large, we tend to recognize the underlying xenophobia today, and that the policies it produced were wrong, bigoted, and self-destructive.

As Islamophobia rears its ugly head in the US again, it's worth thinking about how we now look back on those moments of American history — and whether we're making the same mistakes again.