Why did the gold-salt trade develop between west africa and north america?

How was slavery in mesoamerica, africa, and the arab world similar? many enslaved people were forced to pledge loyalty to their owners. many enslaved people worked in exchange for protection from foreigners. many enslaved people were captured during war. many enslaved people taught and tutored children.

During wwi, literacy tests were used to control immigration, which marked a return of what type of ideology in some americans?

What was herbert hoover and the food administration do in wwi?