On Jan. 9, the Duke of Edinburgh, 60, stepped out in the U.S. capital city to pay respects to the nation’s 39th president, who died on Dec. 29 at 100 years old. Prince Edward sat beside Prime Minister Justin Trudeau of Canada, a Commonwealth country and crown realm, for the solemn service.

The Duke of Edinburgh, 60, sat next to Canadian Prime Minister Justin Trudeau inside the Washington National Cathedral. He is the only royal in attendance at the state funeral today. It's as yet unclear if he will carry out any other engagements while in the United States.

As Prince Edward is set to attend the state funeral of Jimmy Carter, a look back at the history of British royals paying tribute to U.S. presidents.