King George VI and Queen Elizabeth became the first reigning British monarchs to visit the United States. Their six day visit lasted from June 7th-12th, 1939, following a visit to Canada. The King and Queen first spent their first two days in Washington, D.C. where they were welcomed by crowds of cheering spectators. After enjoying receptions, entertainment, and site seeing in Washington, D.C., the King and Queen traveled with President and First Lady Roosevelt to their home in Hyde Park, NY. The purpose of bring the royal couple to Hyde Park was to demonstrate the reliability of the King and Queen to the American public, especially in an area of growing isolationist sentiment. Here they ate a traditional American picnic: hot dogs (the king and queen's first ever), ham and turkey, and strawberry shortcake.
King George VI at the picnic in Hyde Park, NY with FDR's mother Sara, New York Governor Herbert Lehman, and Elinor Morgenthau (the wife of Treasury Secretary Henry Morgenthau) (June 11, 1939)
The visit also included discussions between FDR and King George VI on Europe's political and military situation. Topics discussed included the U.S. Navy providing support for the Royal Navy and the "destroyers for bases" deal, signed two months later, in which the U.S. provided naval destroyers to Great Britain in exchange for for British land rights in Bermuda, Newfoundland, Argentina, and the West Indies.
The King and Queen enjoyed their visit and Queen Elizabeth wrote to her mother-in-law Queen Mary: "They are such a charming and united family and living so like English people when they come to their country house." On the American side, the Royal visit did a lot to improve American impressions of the British from either foreign strangers or colonial rulers, to familiar allies. This impression became helpful for gathering the public support for America to support the Allies in WWII, which began a few months later on September 1, 1939.