The United States
Locating a Relative in the U.S.
The Social Security Administration
The Social Security Administration has established a letter forwarding procedure to meet compelling humanitarian needs. Where there is mental anguish, serious illness, or a death in the immediate family, that agency will attempt to forward a letter to the missing person through his or her last employer. Also, where there is a sizable monetary consideration -- such as an inheritance--due the person (of which he or she is not aware), such an attempt will be made. To ask the agency to forward a letter in your case, send a letter for the person, along with a brief letter of explanation addressed to the:
Social Security Administration
Attention: OFFICE OF PUBLIC INQUIRES
Baltimore, Maryland 21235
U.S.A.
The letter for the missing person should be in a plain unsealed stamped envelope bearing his or her name and social security number, with nothing of value enclosed. (If the social security number is unknown, you should include other identification such as the person's date and place of birth, father's name and mother's maiden name.) The agency will be unable to report whether the letter is actually delivered.
Other sources:
Another way to locate relatives is to use online telephone directories such as: