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 Eisenhower's grandson.
George Washington's half aunt married James Madison's half first cousin once removed.
Woodrow Wilson married (as his second wife) the great-great-great-niece of Thomas Jefferson. Presidents related to European royalty
This is a list of presidents of royal descent.
Note that since all of these Presidents are related to English or Scottish monarchs, they are also all related to each other, though very distantly.