The face mask is a political symbol in America, and what it represents has changed drastically in the 100 years since the last major pandemic

• Mask laws were enacted in the US during the Spanish flu pandemic of 1918, and wearing one was seen as a proud exhibition of one's patriotic duty to their country.
• Fast forward to the coronavirus pandemic of 2020, and that's in stark contrast with some mask protesters perceiving the face coverings as un-American.

A divisive "health versus the economy" debate has emerged, as the coronavirus disease has infected 1.7 million people in the US and continues to spread. Liberals have advocated for lengthier lockdowns and more staunch compliance with public safety precautions, while the Conservatives have largely pushed for the reopening of the nation's economy.

An unlikely item — the face mask — has become symbolic of that discourse.

Mask-wearing laws vary by state and city, and the vast majority of Americans, including Republicans and those who support Trump, say they regularly cover their faces to prevent the spread of the coronavirus disease, according to recent national surveys.

But political affiliation has still become a factor in many Americans' decision to wear a mask. According to a poll conducted by The Associated Press-NORC Center for Public Health Research, 76% of Democrats said they're more likely to wear a mask in public compared with 59% of Republicans.

Politicians themselves have become examples of the divide. President Donald Trump and Vice President Mike Pence have refused to wear them on several occasions. Former Vice President Joe Biden has called the president a "fool" for giving in to "falsely masculine" behavior instead of wearing a mask.

According to an AP report, the president believes his public image and chances of reelection could be damaged if he dons a mask, which would lead voters to believe he was more concerned with public health than refueling the economy.

Retail workers are fielding the bulk of the backlash from anti-maskers, who are blowing off mask policies put in place by businesses, states, and local governments, as Business Insider's Kate Taylor and Áine Cain report.

"The employees are downright afraid to ask people to put on masks," Kroger employee and Michigan resident Kristine Holtham told reporters recently. "Believe me, if you ask someone to put on a mask, it's like asking them to throw their gun away." A security guard in Michigan was shot and killed after turning away a customer for not wearing a mask upon entering a Family Dollar store.

It may have initially seemed unlikely that such a flimsy object could bear so much weight in the country's divided response to the disease. But this isn't the first health crisis in which mask-wearing has been politicized.

During the Spanish flu pandemic of 1918 and 1919, masks were a symbol of patriotism

Nationwide, officials urged people in 1918 to don gauze masks and face coverings or cover their mouths and nose with handkerchiefs in the event of a sneeze or cough to help in the prevention of the spread of influenza.

The public health messaging and posters largely depicted men and boys, who were seen as the "weak links in hygienic discipline" during that wartime period, according to a 2010 report published in the US National Library of Medicine. Men perceived masks as a threat to their masculinity, associating the hygienic practice with passive motherly figures.

So health officials campaigned to rebrand personal care as a display of red-blooded patriotism, incentivizing men to do their part in stemming the spread of the disease by appealing to their sense of civic duty.

Wearing masks during the Spanish flu pandemic was a proud exhibition of one's devotion to their country, especially as World War I was coming to an end.

There was mostly widespread compliance, but just like during the coronavirus, anti-mask sentiment was present during the flu pandemic. San Francisco was a hotspot for such rhetoric.

The city implemented laws enforcing residents to wear masks in public at two different times. The first was in October 1918, when the number of flu cases peaked during fall. The second was in January 1919, after there was a surge in cases following a premature reopening of the city and after hundreds were arrested for flouting the mask order.

A violent altercation even erupted between a mask-slacker and a health inspector, who shot the perpetrator.

The "Anti-Mask League of 1919" was formed to aggressively push back on the law reinstated by officials the second time. Some members cited the uncertainty of the mask's efficacy in preventing infection as a reason for joining.

The mayor initially stood his ground, saying at the time that "we should give our minds to serious matters instead of fighting the little inconvenience occasioned by the wearing of a mask for the protection of the general public," according to records of a Board of Supervisors meeting.

After San Francisco emerged from its Fall 1918 lockdown too soon — and after hundreds ignored the mask order and residents formed the league — the city wound up with one of the highest death rates in the country. The mask law was dropped on February 1, 1919, after the case counts dipped.

Are masks 100% effective? No, but they help

The most effective way to prevent respiratory viruses — including the flu and COVID-19 — from spreading is to lower the chance that a respiratory droplet from someone who is infected lands on someone else, thereby infecting them.

Implementing social distancing measures as early as possible — as well as sustaining them — is the most straightforward way to do that.

Masks are not a silver bullet in preventing the spread of the coronavirus disease, and they weren't 100% effective in stunting the spread of influenza in 1918 either. Many during the 1918 pandemic used gauze to construct masks, a porous material that is nothing like the sturdier N95s and other forms of masks used today.

Experts can't seem to come to an agreement, partly because so much mystery remains about the novel coronavirus. Since the beginning, official advice on the use of face masks during the COVID-19 crisis has been ever-changing, as Insider's Gabby Landsverk reports. But the general consensus is that masks do aid in slowing the transmission throughout populations.

The US Centers for Disease Control and Prevention advise all Americans to wear masks or cover their faces when in public.

The nation's leading infectious disease expert, Dr. Anthony Fauci, told CNN that he wears a face mask as an example for the general public to do the same out of respect for their fellow Americans.

"I want to protect myself and protect others, and also because I want to make it be a symbol for people to see that that's the kind of thing you should be doing," Fauci told CNN's Jim Sciutto.