Actually, I have to correct myself. It was widely reported that this was the first presidential Day of Mourning since LBJ's death in 1973, but that turns out to be false. According to a couple of pieces online, including one at Google Answers (http://answers.google.com/answers/threadview?id=361043), there was a National Day of Mourning for Nixon in 1994. The practice began with Kennedy, and there has been a National Day of Mourning for every president who has died since 1963. However, I don't know if the stock markets closed for any previous president.
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How were other Presidents who served full terms with no resignation treated?
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