It's fairly easy to figure out who the wealthiest person in the United States is. Just look at the Forbes 100, and you see it's Bill Gates, worth $67 billion. Carlos Slim, the Mexican titan, is worth $73 billion, a measly nine percent more. And with a bit of Googling, you could find similar answers for people across history. The famous Roman politician Marcus Crassus was thought to be among the republic's wealthiest, with a net worth of 200 million sesterces. Fast forward through time, and John D. Rockefeller is said to have had a peak of $1.4 billion in 1937.