Columbus's voyages inaugurated what historians call the Columbian Exchange: the transfer of plants, animals, precious metals, diseases, technologies, and peoples between the Old World and the New. American crops such as maize and potatoes eventually reshaped diets across Europe, Asia, and Africa, while livestock, iron tools, and European diseases moved in the opposite direction with catastrophic effect on the peoples Columbus encountered.

The human cost on the Caribbean side of that exchange was severe. The Taino population of Hispaniola, estimated at several hundred thousand to about a million at the time of Columbus's arrival in 1492, was reduced to only a few hundred individuals within roughly three decades, driven by forced labor, violence, and epidemic disease - including a 1493 swine influenza outbreak and, from 1518 onward, smallpox. Across the Americas as a whole, historians estimate that 85 to 95 percent of the indigenous population died from the first contact of Columbus's voyages through the mid-1600s.

Ironically, the continents Columbus reached were not named for him but for the Florentine explorer Amerigo Vespucci, credited with recognizing that the Americas were a previously unknown landmass rather than the eastern edge of Asia, a conclusion Columbus himself refused to accept even after four voyages. Columbus Day and numerous statues, place names, and institutions across the Americas nonetheless still bear his name, a legacy built largely in the centuries after his death as European nations idealized his voyages as heroic acts of discovery.

That idealized image has been substantially revised by modern scholarship and public awareness of the violence his governorship inflicted on the Taino people of Hispaniola, and many places and institutions have reconsidered how, or whether, to commemorate him. What is not in dispute is the scale of what his 1492 landfall set in motion: sustained contact between the Old World and the Americas that reshaped diets, economies, disease patterns, and populations on every continent involved.

Michael Hart ranked Columbus 9th in The 100, summarizing his significance in a single line: his discovery of the Americas led to worldwide exploration. Unlike Cai Lun and Gutenberg, ranked just above him for specific inventions, Columbus's influence rests on a single voyage and its consequences - a demonstration that a westward Atlantic crossing was possible, which within decades sent Spanish, Portuguese, English, French, and Dutch ships chasing territory, trade, and resources across the globe.

Columbus died in 1506 believing to the end that he had found a new route to Asia rather than an unknown continent, a misunderstanding that in no way diminished the scale of what followed: European colonization of the Americas, the Columbian Exchange of crops, animals, and diseases between hemispheres, and a reordering of global power that still shapes the modern world more than five centuries later.