Final answer:
Christopher Columbus claimed Puerto Rico for Spain in 1493, contributing to the expansion of the Spanish Empire following his second voyage. The Treaty of Tordesillas in 1494 further legitimized Spanish claims in the New World. Puerto Rico remained under Spanish control until it was ceded to the United States in 1898.
Step-by-step explanation:
In 1493, Christopher Columbus claimed the island of Puerto Rico for Spain following his second voyage to the Americas. This event was part of the Spanish efforts to expand their influence in the New World after Columbus's initial discovery in 1492. Although the island had been populated by Amerindian peoples for centuries, the Spanish Crown took formal control, and Puerto Rico remained under Spanish rule for over 400 years before being ceded to the United States in 1898 as a consequence of the Spanish-American War.
The geopolitical climate of the late 15th century was marked by competition between maritime powers, primarily Spain and Portugal. The Spanish influence was solidified when Pope Alexander VI, who was Spanish by birth, issued a decree in 1493 that divided the non-Christian world between Spain and Portugal, west and east of a certain line, respectively. This line was later ratified by the Treaty of Tordesillas in 1494. This treaty and the following claims and settlements led to the significant extension of the Spanish Empire's reach across the Americas and into the Pacific.