Beginning Monday, September 23, 2013, The United Nations General Assembly (UNGA) will be in session for approximately 10 days. The NYPD advises us that all streets, avenues, roads etc. - are subject to "spontaneous" closings.
Below is the link that will provide you with the necessary street closures in and around the UN. http://www.nbcnewyork.com/news/local/United-Nations-Gridlock-General-Assembly-Street-Closures-170988291.html