The first formal cautions about Puerto Rico appeared during the 16th century, when Spanish explorers noted the island’s strategic position and the threats posed by rival European powers and indigenous resistance. These early warnings were not government‑issued but rather informal notices shared among merchants and colonial administrators, highlighting the risks of piracy and disease. Over time, as the island’s political status solidified under Spanish rule, official documents began to codify travel risks, particularly during periods of conflict such as the Spanish–American War and the subsequent U.S. occupation.
In the 20th and 21st centuries, the nature of travel warnings shifted from military and health concerns to encompass natural disasters—hurricanes, earthquakes—and socio‑political instability. The 1994 Hurricane Hugo and the 2005 Hurricane Maria, for example, prompted international advisories on evacuation and infrastructure resilience. More recently, evolving security protocols and the global rise of terrorism have led to periodic travel alerts issued by U.S. State Department officials, reflecting a nuanced assessment of safety for visitors today.