Mercer County, New Jersey has the distinction of hosting the city of Trenton, which serves as the State Capitol as well as the county seat. The United States Census Bureau considers much of Mercer County to still be technically included in the New York City Metropolitan Area. At the same time, it is also very close to the Philadelphia Metropolitan area.
This, of course, means more than arguments between the two cities’ sports fans. It also means that Trenton and Mercer County are popular places to live for commuters who work in both metropolitan centers.