Why did america use africans for slaves instead of indians?

Most of the native North Americans, like the native South Americans, were killed off within a few decades of contact with Europeans by disease. As much as 90% reduction in population. Columbus made slaves of the natives on the islands until they were sharply reduced and his colonists started bringing in Africans as slaves.

The ones that did not die did not make good slaves because Native Americans could easily escape - they knew the country, knew how to live off the country, knew the language, and wouldn't have any problems being on their own. Africans, on the other hand, didn't know the language, didn't know the country, were totally unaccustomed to the type of terrain, climate, available 'wild' food etc.etc.etc. If they escaped, they had nowhere to go.