Ok, so I'm watching "Welcome to Mooseport" right now and one of the characters is the former president of the USA, except everyone refers to him as "The President" or addresses him as"Mr President".

I was surprised and goggled this but couldn't find anything on the subject. Do you still address a former president as "Mr President" and if so why?

 

My understanding on this is that if you are referring to a previous president in a written article the correct term is "Ex-President". If you meet the Ex-President personally he remains entitled to the honorific of "Mr President".

Thus when you have a press conference with a number of Ex Presidents present and some journalist calls out "Mr President" - they all look around.

You may find something here?? - http://www.state.gov/