For the last 50 years the price of a slice of pizza and the New York subway fare has been the same, and if the one increases, so does the other!
What do the New York subway fare and an off-the-street slice of pizza have in common? Well, since the 1960s, they've costed the same!
This very strange correlation was first observed in 1980 by a native New Yorker, Eric M. Bram. He said that, since the 60s, the price of a slice of pizza "matched, with uncanny precision, the cost of a New York City Subway token (good for one ride)."
After his observation of this bit of information, quite a few people looked into it and confirmed that this was indeed true.
Writer, historian and film critic George Fasel even wrote about this correlation in 'The New York Times’ in 1985. In early 2002 Clyde Haberman, a columnist for The NYT coined the term ‘Pizza Connection.’
The ‘New Yorker’ validated that one can actually predict the rise of pizza prices should the subway fare increase and visa-versa. The 'Pizza Connection' was renamed and it is now known as the ‘pizza principle.’
In 2005 and 2007 pizza prices increased and concerns were raised that the cost of the subway fare would subsequently increase as well because of the pizza principle. Again the correlation was proven true when the fare did indeed increase to $2.25 in June 2009 and to $2.50 in 2013.
This connection between pizza and subway fares is rather humorous, but in all fairness, it's a historically accurate economic law!