Final answer:
Colonization in the Americas commenced around 15,000 years ago with the migration of humans via a land bridge from Siberia to Alaska, predating Columbus' 1492 voyage by thousands of years.
Step-by-step explanation:
The first process of colonization in the Americas took place about 15,000 years ago. This was long before the arrival of Christopher Columbus in 1492, who is commonly credited with the discovery of the New World.
However, archaeological and historical research has revealed evidence of an even earlier contact between the Old World and the New World, which happened nearly 500 years before Columbus.
This early presence of humans in the Americas is attributed to migrations over a land bridge between Siberia and Alaska during the last Ice Age, approximately 11,000 years ago, though some argue for an even earlier arrival based on recent discoveries and radiocarbon dating of samples such as charcoal from ancient fires.