Kogs, nobody has to set foot in Boston on Patriot's Day in order for there to be a great start for Amazing Race 13. Either Concord or Lexington would provide a stunning starting point of truly historic proprtions (it was April 19, 1775 but celebrated on Patriots Day in Massachusetts which this year is April 21). So, camera permits there if townships even bother with such things. For East Boston they probably have more infrastructure since things do happen at Logan Airport from time to time, so definitely filming permits there.
GMAN, I am not saying that this is the only possible starting city. Last time we were focused on cities headed for Latin America. The list for Europe is quite different. Let me offer a 17 Eastern Time Zone cities with nonstop flights besides Boston and New York metro(already been there and done that):
Philadelphia
Pittsburgh
Cleveland
Columbus
Cincinnati
Detroit
Indianapolis
Louisville
Baltimore
Washington DC
Nashville
Atlanta
Orlando
Tampa
Jacksonville
Charlotte
Raleigh/Durham
Each one has a small probability attached to it. However, I see Boston as having a much larger probability, maybe almost half.