Mercer County
County
The New Jersey State House and its golden dome at Trenton in 2006
Flag Seal
Nickname:  The Capital County[1]
Location within the U.S. state of New Jersey
New Jersey's location within the U.S.
Coordinates: 40°17′N 74°42′W / 40.28°N 74.70°W / 40.28; -74.70
Country	United States
State	New Jersey
Founded	1838
Named for	Hugh Mercer
Seat	Trenton[2]
Largest municipality	Hamilton Township (population) Hopewell Township (area)
Government
• County executive	Brian M. Hughes (D, term ends December 31, 2023)
Area [3]
• Total	228.86 sq mi (592.7 km2)
• Land	224.44 sq mi (581.3 km2)
• Water	4.42 sq mi (11.4 km2)  1.9%
Population  (2020)[4][5]
• Total	387,340
• Estimate  (2022)[4][6]	380,688
• Density	1,724.9/sq mi (666.0/km2)
Congressional districts	3rd, 12th
Website	www.mercercounty.org

Mercer County is a county located in the U.S. state of New Jersey. Its county seat is Trenton, also the state capital,^[2] prompting its nickname The Capital County.^[1] Mercer County alone constitutes the Trenton–Princeton metropolitan statistical area^[7] and is considered part of the New York combined statistical area by the U.S. Census Bureau,^[8][9][10] but also directly borders the Philadelphia metropolitan area and is included within the Federal Communications Commission's Philadelphia Designated Media Market Area.^[11] The county is part of the Central Jersey region of the state.^[12]

As of the 2020 United States census, the county retained its position as the state's 12th-most-populous county,^[13] with a population of 387,340,^[4][5] its highest decennial count ever and an increase of 20,827 (+5.7%) from the 366,513 recorded at the 2010 census,^[14] which in turn had reflected an increase of 15,752 (+4.5%) from the 350,761 enumerated at the 2000 census^[15][16][17] The most populous municipality in Mercer County at the 2020 census was Hamilton Township, with 92,297 residents,^[5] while Hopewell Township was the largest in area.^[3]

The county was formed by an act of the New Jersey Legislature on February 22, 1838, from portions of Burlington County (Nottingham Township, now Hamilton Township), Hunterdon County (Ewing Township, Lawrence Township, Trenton, and portions of Hopewell Township), and Middlesex County, (West Windsor Township and portions of East Windsor Township).^[18] The former Keith Line bisects the county and is the boundary between municipalities that previously had been separated into West Jersey and East Jersey.

Trenton–Mercer Airport in Ewing Township is a commercial and corporate aviation airport serving Mercer County and its surrounding vicinity. The official residence of the governor of New Jersey, known as Drumthwacket, is located in Princeton, and is listed on both the U.S. National Register of Historic Places and the New Jersey Register of Historic Places. Mercer County contains 12 municipalities, the fewest of any county in New Jersey, and equal to Hudson County.

Trenton-New Brunswick Turnpike, the future U.S. Route 1 through Mercer County, 1904

Holder Tower in Princeton University, one of the world's most prominent research universities^[19]

Etymology

The county was named for Continental Army General Hugh Mercer, who died as a result of wounds received at the Battle of Princeton on January 3, 1777.^[20] Continental Army Brigadier General Hugh Mercer served in the Continental Army during the Battle of Trenton and the Battle of Princeton in 1777. A Scotsman that fled to British North America after the failed Jacobite Rebellion, he worked closely with George Washington in the American Revolution. On January 3, 1777, Washington's army was en route to Princeton, New Jersey. While leading a vanguard of 350 soldiers, Mercer's brigade encountered two British regiments and a mounted unit. A fight broke out at an orchard grove and Mercer's horse was shot from under him. Getting to his feet, he was quickly surrounded by British troops who mistook him for George Washington and ordered him to surrender. Outnumbered, he drew his saber and began an unequal contest. He was finally beaten to the ground, bayoneted repeatedly (seven times), and left for dead. Legend has it that a beaten Mercer, with a bayonet still impaled in him, did not want to leave his men and the battle and was given a place to rest on a white oak tree's trunk, and those who remained with him stood their ground. The Mercer Oak, against which the dying general rested as his men continued to fight, appears on the county seal and stood for 250 years until it collapsed in 2000.^[21]

History

Founded February 22, 1838, from portions of 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 25–26, 1776, General George Washington led American forces across the Delaware River to attack the Hessian forces in the Battle of Trenton on the morning of December 26, also known as the First Battle of Trenton. Following the battle, Washington crossed back to Pennsylvania. He crossed a third time in a surprise attack on the forces of General Charles Cornwallis at the Battle of the Assunpink Creek, on January 2, 1777, also known as the Second Battle of Trenton, and at the Battle of Princeton on January 3. The successful attacks built morale among the pro-independence colonists.^[22] Ewing Church Cemetery in Ewing is one of the oldest cemeteries in the area, having served the Ewing community for 300 years. It is home to the burial places of hundreds of veterans from The Revolutionary War to the Vietnam War.^[23]

Since 1790, Trenton has served as the state's capital, earning the county the name "the Capitial County." After the Legislature relocated to Trenton from Perth Amboy in 1790, it purchased land for £250 and 5 shillings and constructed a new state house, designed by Philadelphia-based architect Jonathan Doane, beginning in 1792. The Doane building was covered in stucco, measured 150 by 50 feet (46 by 15 m), and housed the Senate and Assembly chambers in opposite wings. To meet the demands of the growing state, the structure was expanded several times during the 19th century. New Jersey, along with Nevada, is the only state to have its capital be located at the border with another state, as Trenton is across the Delaware River from Pennsylvania.

The county experienced rapid urbanization and population growth during the first half of the 20th century due to the growth of industrialization in places such as the city of Trenton. Mercer County has the distinction of being the famed landing spot for a fictional Martian invasion of the United States. In 1938, in what has become one of the most famous American radio plays of all time, Orson Welles acted out his The War of the Worlds invasion. His imaginary aliens first "landed" at what is now West Windsor Township. A commemorative monument is erected at Grover's Mill park.^[24]

There were 27 Mercer County residents killed during the September 11 attacks in Lower Manhattan. A 10-foot (3.0 m) long steel beam weighing one ton was given to the county by the Port Authority of New York and New Jersey in March 2011 and is now displayed at Mercer County Park.^[25]

Geography and climate

According to the U.S. Census Bureau, as of the 2020 Census, the county had a total area of 228.86 square miles (592.7 km²), of which 224.44 square miles (581.3 km²) was land (98.1%) and 4.42 square miles (11.4 km²) was water (1.9%).^[3]

The county is generally flat and low-lying on the inner coastal plain with a few hills closer to the Delaware River. Baldpate Mountain, near Pennington, is the highest hill, at 480 feet (150 m) above sea level.^[26] The lowest point is at sea level along the Delaware River.

Demographics

Economy

Based on data from the Bureau of Economic Analysis, the county had a gross domestic product of $36.0 billion in 2021, ranked seventh in the state and a 6.7% increase from the prior year.^[34]

In 2015, the county had a per capita personal income of $63,720, the sixth-highest in New Jersey, and ranked 121st of 3,113 counties in the United States.^[35][36] Mercer County stands among the highest-income counties in the United States, with the Bureau of Economic Analysis having ranked the county as having the 78th-highest per capita income of all 3,113 counties in the United States (and the sixth-highest in New Jersey) as of 2009.^[37] Trenton's role as New Jersey's state capital contributes significantly to Mercer County's economic standing. 9.5% of the population is considered at or below the poverty line.

The median household income in Mercer County is $83,306. 89.6% of the population has a high school diploma, and 43.5% of the county's population has a bachelor's degree or higher, one of the highest rates in the state, as of the 2020 census.^[4]

Government

County government

Mercer County Courthouse in Trenton

Drumthwacket, the official residence of the Governor of New Jersey, is located in Princeton and is listed on both the U.S. National Register of Historic Places and the New Jersey Register of Historic Places.

Mercer County has a county executive form of government, in which the Mercer County Executive performs executive functions, administering the operation of the county, and a Board of County Commissioners acts in a legislative capacity.^[38][39][40] The county executive is directly elected to a four-year term of office. The seven-member Board of County Commissioners, previously known as the Board of Chosen Freeholders, is elected at-large to serve three-year staggered terms of office on a staggered basis, with either two or three seats up for election each year. The Board is led by a Commissioner Chair and vice-chair, selected from among its members at an annual reorganization meeting held in January. The Commissioner Board establishes policy and provides a check on the powers of the County Executive. The Board approves all county contracts and gives advice and consent to the County Executive's appointments of department heads, and appointments to boards and commissions. The Commissioner Board votes to approve the budget prepared by the Executive after review and modifications are made.^[41] In 2016, freeholders were paid $29,763 and the freeholder director was paid an annual salary of $31,763.^[42] That year, the county executive was paid $164,090 per year.^[43]

As of 2024, the Mercer County Executive is Daniel R. Benson (D, Hamilton Township) whose term of office ends December 31, 2027.^[44] Mercer County's Commissioners are (with terms for chair and vice chair ending every December 31st):

Commissioner	Party, Residence, Term
Chair John A. Cimino	D, Hamilton Township, 2026[45]
Vice Chair Kristin L. McLaughlin	D, Hopewell Township, 2024[46]
Samuel T. Frisby Sr.	D, Trenton, 2024[47]
Cathleen M. Lewis	D, Lawrence Township, 2025[48]
Nina D. Melker	D, Hamilton Township, 2025[49]
Terrance Stokes	D, Ewing Township, 2024[50][51][52]
Lucylle R. S. Walter	D, Ewing Township, 2026[53]

Pursuant to Article VII Section II of the New Jersey State Constitution, each county in New Jersey is required to have three elected administrative officials known as "constitutional officers." These officers are the County Clerk and County Surrogate (both elected for five-year terms of office) and the County Sheriff (elected for a three-year term).^[54] Mercer County's constitutional officers are:

Title	Representative
County Clerk	Paula Sollami-Covello (D, Lawrence Township, 2025),[55][56]
Sheriff	John A. Kemler (D, Hamilton Township, 2026)[57][58]
Surrogate	Diane Gerofsky (D, Lawrence Township, 2026).[59][60][61]

No Republican has won countywide office since 2000. Law enforcement on the county level is provided by the Mercer County Sheriff's Office and the Mercer County Prosecutor's Office. The Mercer County Prosecutor is Angelo J. Onofri of Hamilton Township, who took office in December 2016 after being nominated by Governor of New Jersey Chris Christie and being confirmed by the New Jersey Senate.^[62][63] Mercer County constitutes Vicinage 7 of the Superior Court of New Jersey.^[64] The vicinage is seated at the Mercer County Criminal Courthouse, located at 400 South Warren Street in Trenton.^[64] The vicinage has additional facilities for the Civil, Special Civil, General Equity, and Family Parts at the Mercer County Civil Courthouse, located at 175 South Broad Street, also in Trenton.^[64] The Assignment Judge for Mercer County is Mary C. Jacobson.^[64]

Politics

Mercer County is a reliably Democratic county; it has gone for Republicans only three times (1956, 1972, 1984) since 1936. In each presidential election of the 21st century, the Democratic candidate earned at least 60% of the vote. Since the 2008 election, every municipality has voted for the Democratic candidate. As of October 1, 2021, there were a total of 265,703 registered voters in Mercer County, of whom 121,653 (45.8%) were registered as Democrats, 41,701 (15.7%) were registered as Republicans and 98,343 (37.0%) were registered as unaffiliated. There were 4,006 voters (1.5%) registered to other parties.^[70]

In 2008, the county voted for Barack Obama by a 35.4% margin over John McCain, with Obama winning New Jersey by 14.4% over McCain.^[71] He won by a similar margin in 2012 and Hillary Clinton did so in 2016. Joe Biden won the county by 40.0% in 2020, the widest margin for anyone since 1964 by winning with 69.1% of the vote (122,532 votes) to Trump's 29.1% (51,641 votes).

In the 2009 New Jersey gubernatorial election, Republican Chris Christie lost the county with 39.27% of the vote (39,769 votes) to incumbent Democratic governor Jon Corzine's 54.51% (55,199 votes), while Independent candidate Chris Daggett won 5.36% of the vote. (5,424 votes). In the 2013 New Jersey gubernatorial election, Republican governor Chris Christie became the only Republican to win the county since 1993 with 51.9% of the vote (48,530 votes) to Democrat Barbara Buono's 46.3% (43,282 votes). In the 2017 New Jersey gubernatorial election, Democrat Phil Murphy won the county 64.9% to (59,992 votes) 33.1% (30,645 votes). In the 2021 gubernatorial election, Republican Jack Ciattarelli received 34.1% of the vote (34,617 ballots cast) to Democrat Phil Murphy's 65.1% (66,151 votes).

Transportation

The Delaware and Raritan Canal in Hopewell Township

Nassau Street in Princeton

Municipalities

Index map of Mercer County municipalities (click to see index)

The 12 municipalities in Mercer County (with 2010 Census data for population, housing units and area) are:^[82]

Sports

Mercer County has a number of large parks. The largest, Mercer County Park is the home for the US Olympic Rowing Team's training center.^[85]

Mercer County is also the home of the Trenton Thunder baseball team, playing in the MLB Draft League, and the Jersey Flight of the National Arena League. The Thunder were formerly the Double-A affiliate of the New York Yankees playing in the Eastern League before the 2021 Minor League reorganization. The minor league hockey team, the Trenton Titans, established in 1999 and operating as the ECHL affiliate of the NHL's Philadelphia Flyers and the AHL's Adirondack Phantoms, disbanded before the start of the 2013–14 season.^[86]

Education

School districts in the county include:^{[89][90][91][92]}

K-12

9-12

• Mercer County Technical Schools

Special

There is a state-operated school, Marie H. Katzenbach School for the Deaf.

Points of interest

• Drumthwacket, The official residence of the Governor of New Jersey located in Princeton
• New Jersey State House, The capitol complex of New Jersey and the meeting point of the state legislature, located at the state capital in Trenton
• Mercer County Park, in West Windsor
• Hamilton Veterans Park
• Mercer County Park September 11 Memorial
• Swaminarayan Akshardham (North America) in Robbinsville, the largest Hindu temple outside Asia
• Assunpink Creek (part)
• Mercer Lake at Mercer County Park
• Griggstown Native Grassland Preserve (part)
• Princeton Battlefield
• Mercer Oaks Golf Course
• Washington Crossing State Park, in Hopewell Township
• Colonial Memorial Park in Trenton
• Lower Trenton Bridge
• Trenton War Memorial
• Trenton Thunder Ballpark
• Grounds for Sculpture, in Hamilton Township

See also

• National Register of Historic Places listings in Mercer County, New Jersey

Notes

References

External links

Wikimedia Commons has media related to Mercer County, New Jersey.

Wikivoyage has a travel guide for Mercer County (New Jersey).

• Official County Website
• Mercer County Library System