The specific circumstances surrounding the disappearances of Earhart and Hoffa only heighten the intrigue.
Whereas Earhart's case involved a romantic mystery of vanishing into some unknown space in the skies, Hoffa's case featured the frightening prospect of disappearing in a place that was anything but far-flung or out-of-sight, a development that continues to fascinate Dan Moldea, author of the book, "The Hoffa Wars."
"The thing that's always put the hook in me is the fact that here was an American citizen, well-known, who was snatched from a public place on a crowded street in broad daylight and was never heard from again," Moldea said. "That's not something that's supposed to happen in the United States."
Hoffa's disappearance has a unique level of intrigue because it was not merely about the man himself, but rather it involved a slew of other prominent figures.
"Hoffa is very much a part of lots of conspiracy theories -- the Marilyn Monroe thing, peddling tapes of JFK with a woman," Moldea said. "He was important on so many different levels."
More than three decades later, speculation runs rampant not only about how and why Hoffa disappeared, but where he ultimately ended up. Maybe buried beneath Giants Stadium in New Jersey? Or even dumped in a Florida swamp?
As time goes on, though, the obsession over what happened to Hoffa, Earhart, Cooper and others has started to fade slightly.
"In my generation, Hoffa was a big name," Moldea said. "I'm 62 and we are very familiar with who he was. But I find it remarkable that I'm finding fewer and fewer people who know."
The interest surrounding Cooper, for instance, has faded even faster, Thompson said, because the criminal was not famous before he pulled off his daring plane heist.
"In the cases of Hoffa and Earhart, we knew these people and then they disappeared," he said. "In the case of Cooper, we have created a sense of celebrity after the fact -- and those things tend not to go [multi-]generational."
Even as the legends of Hoffa and Earhart slowly start to wane with each generation, new unsolved mysteries that will become part of the American folklore of the 21st century are sure to arise.
"I think cases like Hoffa and Earhart may go away with time, but new ones will take their place," Paulides said.