What was the year when the slave trade started?

Answer 1

the portuguese

1640, Maryland became the first colony to institutionalize slavery. In 1641, Massachusetts, in its written legislative Body of Liberties, stated that "bondage was legal" servitude, at that moment changing the conditions of the African workers - they became chattel slaves who could be bought and solely owned by their masters

FROM: http://www.liu.edu/cwis/cwp/library/aaslavry.htm#beginning

before this it wasn't considered slavery. they were indentured servants in Virginia, but that's like slavery from my perspective.

even prior to this the Spanish used slavery after the encomienda system started to flunk out in modern day central and south America, so they replaced the system with African American slavery. I'm not sure the exact year though.