Al Gore
Flickr photo by simone.brunozzAl Gore's separation from wife Tipper may not be rare in Washington, but it's unusual for vice presidents.

Of the 47 to date -- including current Vice President Joe Biden who was widowed -- Tipper and Al have few other VP and Second Lady examples to look to as they navigate possible divorce.

So who has been through this difficult process?

Nelson Rockefeller -- VP under Gerald Ford. Rockefeller's first marriage to Mary Todhunter Clark, mother of five of his seven children, ended in divorce while he was still governor of New York.

There has been just one divorced man to win the presidential nod too -- Ronald Reagan was married and had children with actress Jane Wyman before the two split and he later married First Lady Nancy Davis.

Considering the pressures of the top two jobs in the nation, are you surprised by these statistics?