School placements for Archie and Lilibet were among factors in the timing.
King Charles III acknowledged "times of great uncertainty" as he expressed gratitude to the American people and marked the 250th anniversary of independence from Britain in a speech to the U.S. Congress that highlighted the bonds between the two countries at a time of political turmoil.
Britain's royal family is leading commemorations for what would be the 100th birthday of the late Queen Elizabeth II.
King Charles III and his wife Queen Camilla are coming to America for their first official state visit to the country.
King Charles and Queen Camilla will make an official state visit to the U.S. this spring, Buckingham Palace said on Tuesday.
The appearance marks the couple's first joint attendance at the awards show in three years.