With Facebook's huge run-up Thursday, Zuckerberg's wealth has shot up by more than $3 billion to $29.7 billion, according to Wealth-X. That's up from a net worth of $20 billion that he hit at Facebook's IPO in 2012. And his net worth has nearly tripled since those dark days of Facebook's post-IPO depression, when Zuckerberg was down to his last $10 billion.
Sure there are plenty of people who are richer than Zuckerberg, including the Google guys who are both worth more than $30 billion. And Bill Gates and Larry Ellison are still the overlords of tech wealth, with $75 billion and $42 billion respectively, according to Bloomberg's Billionaires Index.
But Zuckerberg may be the richest 29-year-old American ever—even adjusted for inflation.
(Read more: Zuckerberg tops list of US philanthropists)
We don't know exactly what Gates was worth in 1984, when he was 29. But in March of 1986, when Microsoft went public, Gates' shares had a public value of around $234 million. Not bad for a 30-year-old. But in today's dollars, that would be around $500 million—not even enough to make the Forbes list.
Of course, after the Google IPO that same year, they soared well past $1 billion each.
As for Ellison, the first reports of his net worth started appearing in the late 1980s, when he was in his 40s and his net worth was put at around $400 million to $500 million.
Granted, there may be some inheritors throughout American history who may have—on an inflation-adjusted basis—been into the billions. But even John D. Rockefeller, Howard Hughes, the Astors and Waltons didn't have fortunes in their 20s equal to $29 billion today.
(Read more: Mark Zuckerberg's staggering tax payments)
It proves once again that the speed of wealth creation today—along with the scale—has never been greater. Someday, perhaps another 20-something will even surpass Zuckerberg's record.
—By CNBC's Robert Frank. Follow him on Twitter @robtfrank.