"I knew I was elected for one reason, to reduce crime," recalls Rudy Giuliani of his 1993 election as mayor of New York. "If I didn't reduce crime, I was going to be thrown out of office. If I did, I would probably succeed."

He succeeded, spectacularly. In recent years, after two terms as mayor, and then a run for the 2008 Republican presidential nomination, Giuliani devotes much of his public time to addressing issues of terrorism and national security. But even after his performance guiding New York through the days after Sept. 11, 2001, Giuliani's greatest accomplishment will always be saving the city from a long-term disaster of crime, insolvency and dysfunction.

Especially crime. The New York homicide rate peaked under Giuliani's predecessor, David Dinkins. In 1993, Dinkins' last year as mayor, 1,927 people were murdered in the city. In 1998, Giuliani's fifth year as mayor, the homicide rate fell to 629 — less than a third the number he inherited. In Dinkins' last year, there were 85,892 robberies; in 1998, there were 39,003. In 1993, there were 100,936 burglaries; in 1998 there were 47,181.

It was a huge victory for Giuliani's smart and aggressive police policies, and it lasted into his second term. Then Michael Bloomberg became mayor and built on many of Giuliani's policies, with much success himself. Now New Yorkers are preparing to choose what might be called their first post-Giuliani mayor, and there are fears of a return to the bad old days.

"Back at the turn of the 1990s, New York City was a mess," Time magazine's Joe Klein wrote recently. "Crime was rampant. The schools were dreadful. ... The mayor was an incompetent. And, above all, the city was run for the benefit of its employees rather than its citizens."

"What followed was 20 years of governance by moderate Republicans, Rudy Giuliani and Michael Bloomberg," Klein continued. "Crime is now at an historic low. The city is booming. There have been improvements in the schools ..." But now, Klein concluded, the liberal Democrats vying to succeed Bloomberg "threaten to return the city to the horrors of the David Dinkins era."

I read part of Klein's assessment to Giuliani when we met at a conference in upstate New York on Monday. "He's absolutely right," Giuliani said. On crime specifically, Giuliani worried that the "broken windows" theory — the idea that a city needs to go after small infractions as energetically as more serious offenses — is not doctrine among today's Democratic mayoral candidates. Giuliani also worries that the high-tech data system he installed for tracking and responding to crime could fall into decline. And he particularly worries about the fate of stop-and-frisk, which he started and Bloomberg continued.

Most of the current Democratic candidates oppose stop-and-frisk. "That indicates to me that they have lost the public safety imperative that I had and that Mike had," says Giuliani.

One reason stop-and-frisk is so important, he explained, is that it amounts to "gun control for bad guys." Compared to other cities — particularly Chicago, now in the grips of a homicide epidemic — "we stop a lot more people, we question a lot more people, and consequently we take more guns out of the hands of bad people."

"Everything we debate has been gun control for good guys," Giuliani said, noting that measures like waiting periods and limits on magazine size are directed mostly at law-abiding citizens. "If you have a waiting period, it's only going to affect good guys. What New York City does is gun control directed toward bad people, which is called enforcement of the law."

A city like Chicago, Giuliani said, has strict gun control laws similar to New York's, but crime is still out of control. It's the enforcement that makes the difference. And it's a huge difference: In 2012, New York had 417 murders — an astonishingly low number for a city of 8.3 million. Chicago, a city a third its size, had 532.

Looking back at his time in office, Giuliani also reflected on his work on welfare, transportation, the city budget and schools. There's a lot at stake in this election, he said. "I think the gains that we made could be lost," Giuliani worried, referring to himself and Bloomberg. "The one that would be lost the quickest is in the area of crime. It doesn't mean we'll go back to as bad as it was, but there's no reason we wouldn't end up having the crime rates that Chicago has if we changed our policies."

Byron York, The Washington Examiner's chief political correspondent, can be contacted at byork@washingtonexaminer.com. His column appears on Tuesday and Friday, and his stories and blogposts appear on washingtonexaminer.com.