President Trump offered several stern warnings Monday to immigrants who might be tempted to vote illegally. If anyone is caught doing so, he told reporters, “there will be prosecutions at the highest level.” He tweeted a separate warning: “Law Enforcement has been strongly notified to watch closely for any ILLEGAL VOTING which may take place” during the midterms.

The good news for the country is that there’s absolutely no evidence that people barred from voting, including immigrants, cast more than a handful of ballots in any election — and many of those are accidental. The nature of covering the news means we can’t say unilaterally that no such rampant fraud occurs, just that there’s no evidence at all that it does.

Perhaps the greatest criminal conspiracy in history, undetected by any outside observer including those looking specifically for it, has been dedicated to shifting the results of elections by getting thousands of immigrants to cast illegal ballots.

Or maybe it’s not happening. Why does Trump say it’s happening? “My opinion,” he said, adding, “and based on proof.” Were he to share that proof, we’d be interested in seeing it.

Also on Monday, the Department of Justice announced the practical ramification of law enforcement being strongly notified. It listed a number of counties and locations around the country which would be monitored for “compliance with the federal voting rights laws.”

At first blush, this sounds a lot like Trump’s deployment of troops to the border right before the midterms, a move that is indistinguishable from the use of federal resources to bolster Trump’s political case. But a little investigation reveals that, in fact, this isn’t new. In 2016, the Justice Department, then under the purview of President Barack Obama, similarly deployed staffers to polling places to ensure the sanctity of the vote.

But there is a key difference between the two.

There are 18 counties that were targeted by Justice in both elections. Attorney General Jeff Sessions’s team dropped 40 counties from the list targeted in 2016 and added 15 new counties for observation.

Comparing those lists with Census Bureau data about each county reveals something interesting. The counties that were dropped by Sessions had an average density of black residents of about 20 percent. The counties he added had an average Hispanic density of 24 percent.

(Philip Bump/The Washington Post)

One of the reasons the Department of Justice monitors polling places is because of the history of voter suppression in elections. That has often meant, particularly in the South, efforts to keep black voters from going to the polls. The shifts in where the department is focusing this year, though, means that the targeted areas are much less heavily black. They’re a bit more densely Hispanic — but this after Sessions’s team cut the number of targeted jurisdictions about in half. (The counties this year are more heavily Native American or Alaska Native on average because Justice dropped a large number of counties that had low densities of those populations.)

(Philip Bump/The Washington Post)

That the department is incorporating Trump’s focus on theoretical immigrant voting into its observations is clear from the statements accompanying the announcements in each year.

In 2016, then-Attorney General Loretta E. Lynch said that the “bedrock of our democracy is the right to vote, and the Department of Justice works tirelessly to uphold that right not only on Election Day, but every day.”

On Monday, Sessions tied voting specifically to citizenship.

“Voting rights are constitutional rights, and they’re part of what it means to be an American,” he said. “Citizens of America control this country through their selection of their governmental officials at the ballot box. Likewise, fraud in the voting process will not be tolerated. Fraud also corrupts the integrity of the ballot."

The good news is that fraud is very, very rare. The Department of Justice, which almost certainly already knows that, will probably be reminded of that Tuesday.