The seven men gunned to death in a Lincoln Park garage on February 14, 1929 — Peter and Frank Gusenberg, Albert Kachellek, Adam Heyer, Reinhardt Schwimmer, Albert Weinshank, and John May — were mobsters. Members or associates of Bugs Moran’s North Side Gang, which competed with Al Capone for control of bootlegging in Chicago, they were just as responsible as their killers for the crime wave that made the Prohibition Era the deadliest decade of the 20th century up to that point.

Still, those violent deaths shocked the American public and led to enormous changes in the nation’s laws and culture — far more than mass murders in our own era.

“The St. Valentine’s Day Massacre fascinated and horrified the American public like no crime since that of Leopold and Loeb,” wrote Chicago author Jonathan Eig in his book Get Capone: The Secret Plot That Captured America’s Most Wanted Gangster. When President Herbert Hoover was inaugurated, less than a month later, he vowed to crack down on the gangsters — especially Capone, who was suspected of ordering the massacre.

Hoover, wrote Eig, persuaded business leaders to fund “a scientific crime laboratory — the nation’s first — to see if new technology used to analyze bullets and guns could help determine who had been responsible for the St. Valentine’s Day Massacre.”

He also promised the Chicago Crime Commission federal aid in bringing down Capone, dispatching a team of Treasury agents to Chicago — including Eliot Ness, who led bootlegging raids and helped escort Capone to prison after he was convicted of tax evasion.

The St. Valentine's Day Massacre was a consequence of Prohibition, which had inspired the formation of gangs to satisfy the nation’s demand for beer and whiskey. It helped convince Americans that lawlessness was a greater evil than liquor and contributed to the 21st Amendment to the U.S. Constitution, repealing Prohibition.

The fact that the victims had been murdered with Thompson submachine guns — so associated with local mobsters they were nicknamed the Chicago Typewriter — led to the passage of the National Firearms Act of 1934, which levied a then-prohibitive $200 tax on the sale of “machine guns,” defined as “any weapon which shoots, or is designed to shoot, automatically or semiautomatically, more than one shot, without manual reloading, by a single function of the trigger.”

Locally, the Massacre led to the defeat of Mayor William Hale “Big Bill” Thompson, who was considered Capone’s man in City Hall. Even the Republican Tribune endorsed Thompson’s Democratic opponent, Anton Cermak, calling him “[t]he chance of escaping four more years of political depravity.” (Cermak went on to found Chicago's version of machine politics, which would dominate the city for most of the 20th century.)

The Massacre’s cultural impact was also enormous. It inspired books and movies, including the opening scene of Some Like It Hot, and made Chicago synonymous with mobsters, an association that didn't begin to dissipate until the Michael Jordan Bulls started winning NBA championships in the '90s.

The St. Valentine’s Massacre is no longer even the deadliest mass shooting to occur on Valentine’s Day. It lost that distinction on February 14th of last year, when 17 students were murdered at Marjory Stoneman Douglas High School in Parkland, Florida. That shooting did lead to a federal ban on “bump stocks,” which enable a semi-automatic weapon to fire at the rate of a machine gun, but there has been no legislation to regulate the weapons themselves, nor is there likely to be.

So how did the deaths of Chicago mobsters spur stricter gun control than the deaths of Florida high schoolers?

Mass shootings were new in the 1920s. Today, they’re commonplace. The Tommy gun, which made the Massacre possible, was first marketed in 1921. Advances in technology have resulted in easily available semi-automatic rifles, such as the AR-15, the modern mass shooter’s weapon of choice. The $200 tax on such weapons isn’t as prohibitive as it was in 1934, when it was the equivalent of $3,800 in modern dollars.

Guns also occupy a different place in American cultural than they did in the 1920s. The National Rifle Association, for instance, helped write the National Firearms Act of 1934. The association’s president told Congress, “I have never believed in the general practice of carrying weapons. I do not believe in the general promiscuous toting of guns. I think it should be sharply restricted and only under licenses.” At that time, the NRA was primarily concerned with marksmanship and gun safety.

Now, the NRA believes in defending the right to bear arms against any government infringement. After 26 children and teachers were murdered at Sandy Hook Elementary School in Connecticut, NRA chief executive Wayne LaPierre gave a speech blaming mass shootings on violent media and suggested they could be prevented by posting armed guards outside schools. (In Dayton last weekend, a gunman killed nine people in 32 seconds before six armed police officers were able to stop him.)

Today, gun control is a partisan issue. Many gun owners feel that firearm legislation would render citizens helpless against government tyranny. Guns are most popular among rural Republican voters, who are overrepresented in the Senate and the Electoral College, making new federal gun laws unlikely. Seating a Supreme Court that will strike down local gun laws is even more unlikely.

Today, the St. Valentine’s Day Massacre is a quaint episode in Chicago history. “Gangster Tour” buses drive by the vacant lot on Clark Street where the shooting took place. Actors in the musical revue Tommy Gun’s Garage dress up in pinstriped suits and wield toy machine guns. The gunmen who killed Moran’s men were pikers compared to today’s mass murderers, but they changed America in a way a modern mass murder haven't.