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Mercer County, New Jersey

Mercer County is a county located in the U.S. state of New Jersey. Its county seat is Trenton6. Since the 2000 Census, Mercer County has been part of the New York Combined Statistical Area; before then, it was part of the Philadelphia Combined Statistical Area. Mercer County is its own Metropolitan Statistical Area, which is formally named the Trenton-Ewing MSA. The county is named for Continental Army General Hugh Mercer, who died at the Battle of Princeton in 1777. As of the United States 2000 Census, the population was 350,761, estimated to have risen to 367,605 as of 2006.[1] Mercer County ranks 79th among the highest-income counties in the United States with a per capita income of $27,914.


Officially founded in 1838 and carved out of other surrounding counties, Mercer County has a historical impact that reaches back to the pivotal battles of the American Revolutionary War. On the night of December 25, 1776, General George Washington led the American forces across the Delaware River to attack Hessian forces in Trenton, New Jersey, who did not anticipate an attack near Christmas. Washington followed up the assault with a surprise attack on General Charles Cornwallis' forces in the Battle of Princeton on the eve of January 2, 1777, eventually retaking the colony. The successful attacks built morale among the pro-independence colonists.

Mercer County also has the dubious distinction of being the famed landing spot for a Martian invasion of the United States. In 1938, in what has become one of the most famous radio plays of all time, Orson Welles acted out his The War of the Worlds invasion. Wells landed his imaginary aliens on Mercer County soil, using what is now West Windsor Township as the point of first contact. A monument commemorating the "landing" is erected at Grover's Mill.

The municipality type is listed in parentheses after the name, except where the type is included as part of the name. Census-designated places and other unincorporated areas are listed under their municipalities.

East Windsor Township
Twin Rivers
Ewing Township
Hamilton Township
Mercerville-Hamilton Square
White Horse
Hightstown (borough)
Hopewell Borough
Hopewell Township
Lawrence Township
Pennington (borough)
Princeton Township
Princeton North
Princeton Borough
Robbinsville Township (known as Washington Township until November 2007)
Trenton (city)
West Windsor Township
Princeton Junction