Author's blurb: This case can be used in introductory or intermediate micro courses. Externalities are among the important concepts covered in introductory economics courses. As such, I like to reinforce and deepen the students' understanding of this concept through discussion and analysis of a real-world example. I use a case about New York City to do so. User summary: Five students are assigned roles on a mayoral panel. The remaining students are divided into interest groups. The class then role-plays a policy presentation and debate with the mayoral panel selecting one of the options presented. Play is intended to be a single course period.