The Continental Congress of the United States of America sent John Jay to Spain in 1779 in an attempt to convince the Spanish Court to recognize the new nation. Jay spent two years there to no success. Madrid was unwilling to risk relations with the Congress in Philadelphia until it became apparent that Britain and the United States were actually going to sign a treaty to end the war and recognized U.S. independence. Since 1783, when Spain did eventually recognize the United States, the two countries have broken relations just once, when they went to war against each other in the Spanish-American War of 1898. Currently Spain is a constitutional monarchy, a member of the European Union and NATO.

The United States opened a consulate in Barcelona on December 29th, 1797. It served briefly as the U.S. Embassy in 1937 during the Spanish Civil War.