why do they call the presidents wife the first lady
http://en.wikipedia.org/wiki/First_Lady#Etymology
The term "First Lady" is a title given to the wife of the President of the United States. It originated in the United States and has been used since the early 1800s. The term "First Lady" was coined by journalist Thomas Fleming in 1877 when he used it to describe Dolley Madison, the wife of President James Madison.
The use of the term "First Lady" reflects the importance and unofficial role that the President's wife plays. The First Lady often takes an active part in public and social affairs, representing the President and the nation on various occasions and promoting important causes.
To find out why the President's wife is called the First Lady, you can research the history of the term and its usage in relation to the role and responsibilities of the President's spouse. Reading biographies or historical accounts of the First Ladies can provide more insight into the origins and significance of the title.