“We’ve gone into towns in Long Island where we’ve taken MS-13 and we’ve actually liberated towns,” President Trump said at an event in West Virginia earlier this month, describing one of his favorite foils, the gang MS-13. “This is our country, right? I grew up in Long Island, right, short of Long Island. And these are great towns; I know every one of them. And they were taken over by thugs.

“These ICE guys are so much tougher than them,” he continued, “and they’re grabbing them by the necks and throwing them into the paddy wagons. And the town — the people are clapping and screaming. Their town has been liberated. It’s like it’s a war.”

Trump traveled to Long Island in July to make the same case. Speaking in front of a group of law enforcement officers in Brentwood, Trump said that “few communities have suffered worse at the hands of these MS-13 thugs than the people of Long Island.” The speech wasn’t really about MS-13 or crime; it was about Trump’s ongoing efforts to portray immigrants from Mexico and Central America as dangerous and to project a sense of his own toughness on the subject. (This was the speech in which he encouraged police to rough up suspects.)

It’s not a surprise, then, that Republicans tried to leverage that same argument in a contested state assembly race just north of where Trump spoke that day. The party sent out mailers like this one, targeting Democratic candidate Steve Stern as being soft on crime.

That argument didn’t work. Stern won the Suffolk County seat by nearly 20 points, taking a district that had been Republican since 1978 and turning it blue.

How is it that Trump won the presidency while arguing about crime while in the place he has consistently described as the epicenter of the worst suffering voters preferred a Democratic candidate? Two reasons. The first is that Trump’s win probably had little to do with his rhetoric on crime, although it probably bolstered support from those whose primary concern in the election was immigration — a group that overwhelmingly backed Trump.

The second reason the crime argument probably wasn’t very resonant is that there’s little reason to think that crime in Suffolk County — or in the communities where Trump spoke and Stern won — is a driving concern.

Suffolk has a unified police department broken into seven precincts. Trump’s speech was in the Third Precinct. Stern’s assembly district is in the Second Precinct. Data from the police department shows that crime in the county has generally been dropping over the past several years, dropping more quickly in the Third Precinct. In Stern’s Second Precinct, crime is up slightly over the past few years, but it’s still lower than it was in 2014.

There was an increase in violent crimes in the Second Precinct from 2016 to 2017 (using the department’s final figures for 2017). But 75 percent of that increase was a function of the number of robberies jumping from 39 to 57 in 2017. The number of murders — a crime that Trump has repeatedly described in agonizing detail as he makes his case against the MS-13 gang — fell from five to one.

In the county overall and in the Third Precinct, violent crime decreased over that period. Over the longer term, crime dropped across the board for both violent and property crimes.

In the Second Precinct, in particular — the area where Stern won — the declines in crime from 2011 to 2016 were substantial. Residents there have every reason to feel safer now than they did five years ago. Data suggest that they are.

Using the specter of criminal thugs waiting to assault and steal is a tried-and-true political tactic. But it loses some of its punch in an era in which criminal activity has declined sharply.

The district Stern won, the 10th, was carried by Hillary Clinton in the 2016 election by seven points. Although Republicans had held the assembly seat for decades, this wasn’t a district that was unlikely to back a Democrat. But the operating theory that leveraging crime and MS-13 would prevent the Democrat from doing so appears to have been hollow.

Then again, it didn’t work for Trump in that district, either.