Many genealogical relationships may be found among Presidents of the United States and between the presidents and other significant figures of history.

Direct descent

The United States Presidents who are related to each other by direct descent are:

Two other pairs of Presidents have shared a surname. Andrew Johnson and Lyndon Johnson have no known relationship. Theodore Roosevelt and Franklin D. Roosevelt were fifth cousins, though they were more closely related through Franklin's wife Eleanor Roosevelt (née Roosevelt), who was Theodore's niece.

Indirect relatives

This is a list of some of the closer blood relations, other than direct descent, between U.S. Presidents. (See Cousin chart to understand the terms used here.)

Second cousins

Third cousins

Fourth cousins

Fifth cousins

Sixth cousins

Seventh cousins

Eighth cousins

Ninth cousins

Tenth cousins

Other relationships

The list above includes the closer, more significant relationships. Family trees, particularly those in a limited geographic area, tend to converge relatively rapidly and many family trees going back ten generations or more will connect to more than one dozen U.S. Presidents, if all female ancestors and their descendants are traced. This is why, for example, it is not mentioned that through Robert Wyngate of Sharpenhoe, Bedfordshire, J.Q. Adams and W.H. Harrison are eighth cousins.

There are also numerous relationships by marriage which are not presented in this article. For example, Richard Nixon was the father-in-law of Dwight D. Eisenhower's grandson. George Washington's half aunt married James Madison's half great-uncle. Woodrow Wilson married (as his second wife) the great-great-great-niece of Thomas Jefferson.

Presidents related to royalty

Presidents related to British royalty

As a result, all of the listed people are direct descendants of Alfred the Great. All but one of them are also descended from William the Conqueror with the exception of Rutherford Hayes. Most of these royal ancestors were born before the Black Death killed much of the population of Britain in 1349.

In addition, according to Genealogics and Roglo, HM Queen Elizabeth II is among the closest living relatives of George Washington, through their descent from Augustus Warner, Burgess of Virginia.

Presidents related to other royalty