A positive effect of the Columbian exchange was the introduction of New World crops, such as potatoes and corn, to the Old World. A significant negative effect was the enslavement of African populations and the exchange of diseases between the Old and New Worlds. A primary positive effect of the Columbian Exchange is increased food supply of both the Old World and the New World. Various crops such as wheat, barley, and rye, were introduced by Columbus and his followers. Though there were positive effects, the Columbian Exchange had a long-lasting negative impact. Christopher Columbus's arrival in the Americas facilitated the exchange of plants, animals and diseases between the Old and New Worlds. For generations, Christopher Columbus was considered a hero of American history. Some of the negative effects of the exchange included the diseases, like smallpox and influenza, that Europeans brought to the "New World." The Native Americans had no prior exposure to these diseases and had not built up any immunity. As a result, these diseases were deadly to them and decimated their populations.
The US's the fear of Radicals and the Bolshevik revolution in Russia. US Police roundedup suspected foreign born radicals and had them expelled from the United States. Fed growing demands to limit immigration.
