Second Amendment absolutists love to point to Chicago as proof that regulating firearms is futile. The syllogism “Chicago has gun control laws, but Chicago has the most murders, therefore gun control doesn't work” is an NRA talking point embraced at the highest levels of the Republican Party.

Many mass shootings ago, after a gunman killed 58 people at a country music concert in Las Vegas, the White House compiled a list of points to argue that it wasn’t a gun that enabled to him to inflict so much mayhem. Among them: "[S]ome of America’s cities with the strictest gun laws have the highest rates of gun violence. Examples include: Chicago last year had over 4,300 shooting victim [sic.]”

The latest and loudest exponent of Whataboutchicagoism is Texas Sen. Ted Cruz, who receives more money from the NRA than any politician and whose state is the site of the last two mass shootings, in El Paso and Odessa.

After the Odessa shooting, Cruz was so eager to let his constituents know he was protecting their gun rights that he tweeted, “Gun control doesn’t work. Look at Chicago. Disarming law-abiding citizens isn’t the answer. Stopping violent criminals — prosecuting & getting them off the street — BEFORE they commit more violent crimes is the most effective way to reduce murder rates. Let’s protect our citizens.”

Mayor Lori Lightfoot was having none of it.

“60% of illegal firearms recovered in Chicago come from outside IL — mostly from states dominated by coward Republicans like you who refuse to enact commonsense gun legislation,” she tweeted back. “Keep our name out of your mouth.”

The tweet was accompanied by a chart showing that 21 percent of the guns recovered in Chicago could be traced to Indiana, which shares a border with the city.

So who's right here? They both are. Cruz is right that Chicago's gun ordinances are ineffective. Lightfoot is right that they’re ineffective because we’re surrounded by states where it's easier to get a gun than a driver’s license. (Indiana and Wisconsin do not require a permit to purchase a gun. Illinois requires a Firearm Owners ID.)

To the larger point, Illinois is part of a country which enshrines gun rights in its constitution. There are 390 million guns in the United States, and we can’t inspect every car that crosses the Chicago border to make sure there’s not one inside. Gun experts made this point in a 2017 NPR story titled “Fact Check: Is Chicago Proof that Gun Control Laws Don’t Work?

It’s important to remember here that Chicago is very close to two states that have relatively weak gun laws: Wisconsin and Indiana. So while it's easy to pick on Chicago (or any other high-crime city) for its ugly statistics, says one expert, taking bordering states into account weakens this gun-advocacy talking point.

“It’s not a scientific study. It's an anecdote,” said Philip Cook, a professor of public policy studies at Duke University. “They might have pointed to Washington, D.C., back in the days when D.C. banned handguns and yet had high gun-violence rates. Those bans are only at best partially effective, because the borders are permeable.”

And there’s good evidence that being next-door to those states keeps Chicago criminals well-supplied with guns. A 2015 study of guns in Chicago, co-authored by Cook, found that more than 60 percent of new guns used in Chicago gang-related crimes and 31.6 percent used in non-gang-related crimes between 2009 and 2013 were bought in other states. Indiana was a particularly heavy supplier, providing nearly one-third of the gang guns and nearly one-fifth of the non-gang guns.

Here in Illinois, we try to restrict the availability of guns to law-abiding citizens, but there’s only so much we can do in this region of the country. Anything goes in Indiana — cheap cigarettes, fireworks, gambling, 200-proof alcohol, and guns. We’re in the same position as the vegan who tried to sue her neighbors over the meat smells coming from their grills.

Gun control can work, but it’s only truly effective when applied at the national level. In 1996, after a man armed with an AR-15 killed 35 people in Australia, the nation banned automatic and semi-automatic weapons, as well as pump-action shotguns. A buyback program collected 640,000 guns. Australia hasn’t experienced a mass shooting since.

It's impossible to imagine the same course of action in the United States, where guns are interwoven into our conception of ourselves as a free people — and where politicians over- and misrepresent the views of gun owners. For that, Cruz can blame himself and his political allies. Chicago’s murders aren't evidence that gun control is a failure. They're evidence of what happens in big cities when a country fails to control guns. Until Cruz has a plan to do that, Lightfoot's got point about him washing Chicago’s name from his mouth.