The middle passage involved shipping slaves from to .

Africans carried to North America, including the Caribbean, left mainly from West Africa. Well over 90 percent of enslaved Africans were imported into the Caribbean and South America. Only about 6 percent of African captives were sent directly to British North America. The "Middle Passage" refers to the journey from Africa to America and the conditions under which these Africans lived. White colonists in the Americas would purchase the enslaved Africans upon their arrival. Africa

The most significant routes of the slave ships led from the north-western and western coasts of Africa to South America and the south-east coast of what is today the United States, and the Caribbean. As many as 20 million Africans were transported by ship. The majority of enslaved Africans went to Brazil, followed by the Caribbean. A significant number of enslaved Africans arrived in the American colonies by way of the Caribbean, where they were “seasoned” and mentored into slave life.

Explanation:

becasue in the south they disallowed slavery but in the north slavery was illegial this boilled into because mexico wanted slavery