On June 7, 1494, the governments of Spain and Portugal agreed to the Treaty of Tordesillas, which divided the “New World” of the Americas between the two superpowers.
Spain and Portugal divided the New World by drawing a line in the Atlantic Ocean, about 370 leagues west of the Cape Verde Islands, then controlled by Portugal. All lands east of that line (about 46 degrees, 37 minutes West) were claimed by Portugal. All lands west of that line were claimed by Spain.
Spain and Portugal adhered to the treaty without major conflict, and the results linger throughout the Americas today. Most Latin American nations are Spanish-speaking countries, for instance, but Portuguese is the leading official language in Brazil. This is because the eastern tip of Brazil penetrates the line agreed to in the Treaty of Tordesillas, so the region was colonized by Portugal. To learn more, see helpful links below:
National Geographic - 1494: Treaty of Tordesillas
Libweb5.princeton.edu - Lines of Demarcation
Let.rug.nl - The treaty of Tordesillas June 7 1494
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