Welcome to
Mercer County
New Jersey
Genealogy and History

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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 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






Church Histories/Records



Newspaper Data


Wills/Probate Records 

Recent Website Updates:

October 2015:
Community News:
29th Annual Commencement of Pennington Female Seminary
Administrators Notice: John Phillips
July 13, 1881 Hopewell Local News

September 2015: Obit: William Parret

Previous Updates

Municipalities within County

East Windsor Township
Ewing Township
Hamilton Township
Hopewell Township
Lawrence Township
Princeton Township
Washington Township
West Windsor Township

Hightstown (borough)
Hopewell Borough
Mercerville-Hamilton Square
Pennington (borough)
Princeton Borough
Princeton Junction
Princeton North
Trenton (city)
Twin Rivers
White Horse


County Seat:
The county seat is Trenton

Since 2000, Mercer County has been considered part of the New York metropolitan area; before that time it had been considered part of the Philadelphia metropolitan area.

The county is named for Continental Army General Hugh Mercer, who died at the Battle of Princeton in 1777.

Surrounding Counties:
Somerset County, New Jersey - north
Middlesex County, New Jersey - northeast
Monmouth County, New Jersey - east
Burlington County, New Jersey - south
Bucks County, Pennsylvania - west
Hunterdon County, New Jersey - northwest

New Jersey State Site


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