New York is the most important source of political fundraising in the United States, as four of the top five ZIP codes in the nation for political contributions are in Manhattan. The top ZIP code, 10021 on the Upper East Side, generated the most money for the 2004 presidential campaigns of George W. Bush and John Kerry. The city has a strong imbalance of payments with the national and state governments. It receives 83 cents in services for every $1 it sends to the federal government in taxes (or annually sends $11.4 billion more than it receives back). The city also sends an additional $11 billion more each year to the state of New York than it receives back.
Try to answer this question if possible (otherwise reply "unanswerable"): Four-fifths of the ZIP codes that provide the highest amount of political contributions in the United States are located in what borough?
Manhattan