Economic motivations played a significant role in the U.S.'s decision to enter the Spanish–American War. Firstly, the U.S. had substantial commercial interests in Cuba, which were jeopardised by the ongoing Cuban struggle for independence against Spanish rule. American businesses had invested heavily in Cuban sugar, tobacco, and other industries, and the instability threatened these investments. Additionally, the war presented an opportunity for the U.S. to open up new markets for its growing industrial output, particularly in territories like the Philippines. The prospect of acquiring new territories was seen as a means to expand American economic influence and access to resources, underscoring the economic underpinnings of the U.S.'s intervention.

The Spanish–American War had a profound impact on U.S. military strategy and doctrine. One of the most significant changes was the recognition of the importance of a modern, powerful navy. The success of the U.S. Navy in the war, particularly in the Battle of Manila Bay, underscored the value of naval power in projecting military strength abroad. This led to a greater emphasis on naval expansion and modernisation in the following years. Furthermore, the war highlighted the need for a more agile and rapidly deployable military force, influencing the U.S.'s approach to overseas military engagements. These strategic shifts laid the foundation for the U.S.'s future military engagements and its emerging role as a global military power.

The outcome of the Spanish–American War significantly altered U.S. relations with European powers. The U.S.'s victory and acquisition of former Spanish territories marked its arrival as an imperial power, which demanded recognition and respect from European nations. This newfound status shifted the dynamics of international relations, with European powers now viewing the U.S. as both a potential ally and a competitor in global affairs. The war also demonstrated the U.S.'s military capabilities, leading to a cautious approach by European powers in their dealings with the U.S., particularly in the Western Hemisphere. Additionally, the U.S.'s interventionist stance post-war occasionally put it at odds with European imperial interests, leading to complex diplomatic interactions in the following decades.

The Spanish–American War played a crucial role in shaping U.S. policies in the Caribbean and Pacific regions. In the Caribbean, the U.S. established a more assertive presence, underscored by the acquisition of Puerto Rico and its increased influence in Cuba through the Platt Amendment, which effectively made Cuba a U.S. protectorate. This set a precedent for future U.S. interventions in the Caribbean. In the Pacific, the acquisition of the Philippines and Guam extended U.S. influence and marked its first major step as a Pacific power. This expansion facilitated increased U.S. involvement in Asian affairs, notably in China with the Open Door Policy, and laid the groundwork for future strategic and military interests in the Pacific. The war thus fundamentally reshaped U.S. foreign policy priorities and strategies in these regions.

The Spanish–American War significantly shifted American public opinion towards a more interventionist foreign policy. Prior to the war, the U.S. largely adhered to a policy of isolationism, focusing on internal affairs and continental expansion. However, the media portrayal of Spanish atrocities in Cuba, particularly through 'yellow journalism', ignited a surge of humanitarian concern and nationalist sentiment. The swift victory in the war bolstered national pride and confidence in the U.S.'s military capabilities. Consequently, this led to greater public support for the U.S.'s role as an international power, encouraging future interventions and expansionist policies. The war effectively transitioned the American public mindset from isolationism to a willingness to engage in overseas conflicts.