The United States goes from looking INWARD to looking OUTWARD.  This includes a
national conversation concerning ideas and opinions that will impact the United States other countries. 

A Review of American Expansion and Conquest

The development of a new steel navy also focused attention overseas. Captain Alfred Thayer Mahan’s book of 1890, The Influence of Sea Power upon History ,1660–1783 , argued that control of the  sea was the key to world dominance. (One of the most influential public policy books ever published)

Mahan analyzed the role a Navy played in history. He determined the US needed to look beyond its borders and have a strong Navy to protect its economic interests.  Nice summary of Mahan's Influence (7 minutes) 

The Spanish-American War By the Numbers…. Cost: $250,000,000 

Combat deaths: 385 American battle deaths (1/20th the number lost at Gettysburg)

Non-combat deaths: 4,000  + deaths from disease and poisoned meat

Acquisitions: Puerto Rico and Guam were ceded (To surrender possession of, especially by treaty) to the United States as indemnity(compensation for a particular loss suffered), and the Philippines were surrendered to the United States for a payment of $20 million.