International trips made by the heads of state and heads of government to the United States have become a valuable part of American diplomacy and international relations since such trips were first made in the mid-19th century. They are complicated undertakings that often require months of planning along with a great deal of coordination and communication.
The first international visit to the United States was made by King Kalakaua of Hawaii in 1874, which was the first visit by a foreign chief of state or head of government.
The first European head of state to visit the United States was Prince Albert I of Monaco in 1913.
Since the 1980s, it is customary for the Taoiseach of the day to visit the White House on Saint Patrick's Day and present the President with a bowl of shamrock.