Mercer County is a county located in the U.S. state of New Jersey. Its county seat is Trenton, also the state capital, prompting the nickname The Capital County. Mercer County alone constitutes the Trenton–Princeton Metropolitan Statistical Area and is considered part of the New York Combined Statistical Area by the United States Census Bureau, but also directly borders the Philadelphia metropolitan area and is included within the Federal Communications Commission's Philadelphia Designated Market Area. As of the 2020 United States Census, Mercer County's population was 387,340, making it the state's 12th-most populous county, an increase of 20,827 (5.7%) enumerated at the 2010 U.S. Census, when its population was enumerated at 366,513, in turn an increase of 15,752 (4.5%) from the 350,761 counted at the 2000 Census, retaining its position as the 12th-most populous county in the state.
The county was formed by an act of the New Jersey Legislature on February 22, 1838, from portions of Burlington County (including Nottingham Township), Hunterdon County (including Ewing Township, Lawrence Township, Trenton and portions of Hopewell Township), and Middlesex County (including West Windsor Township and portions of East Windsor Township). The former Keith Line bisects the county and is the boundary between municipalities that previously had been separated into West Jersey and East Jersey. It 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. 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.
Mercer County is home to Princeton University, Princeton Theological Seminary, the Institute for Advanced Study, Rider University, Westminster Choir College, The College of New Jersey, Thomas Edison State University and Mercer County Community College. 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.
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.
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.
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.
There were 27 Mercer County residents killed during the September 11, 2001 terrorist attacks in Lower Manhattan. A 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.
Geography
According to the 2010 Census, Mercer County had a total area of , including of land (98.1%) and of water (1.9%).
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 above sea level. The lowest point is at sea level along the Delaware.
Adjacent 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
Climate
Most of Mercer has a hot-summer humid continental climate (Dfa) except for lower areas of Trenton and along the Delaware in Hamilton Township where a humid subtropical climate (Cfa) exists. The hardiness zones are 6b and 7a.
Demographics
2020 Census
2010 Census
Economy
Based on data from the Bureau of Economic Analysis, Mercer County had a gross domestic product (GDP) of $28.5 billion in 2018, which was ranked 9th in the state and represented an increase of 2.3% from the previous year.
In 2015, the county had a per capita personal income of $63,247, the sixth-highest in New Jersey and ranked 121st of 3,113 counties in the United States. 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. Trenton's role as New Jersey's state capital contributes significantly to Mercer County's economic standing.
Law and government
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.
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, formerly known as Freeholder 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. In 2016, freeholders were paid $29,763 and the freeholder director was paid an annual salary of $31,763. That year, the county executive was paid $164,090 per year.
, the County Executive is Democrat Brian M. Hughes of Princeton, who was re-elected to a fifth four-year term in November 2019 and is serving a term of office ending December 31, 2023. Mercer County's Commissioners (formerly Freeholders) are:
Freeholder Chair Pasquale "Pat" Colavita Jr. (D, term as freeholder ends December 31, 2018, term as chair ends 2017; Lawrence Township)
Freeholder Vice Chair Lucylle R. S. Walter (D, term as freeholder and as vice chair ends 2017; Ewing Township)
Ann M. Cannon (D, 2018; East Windsor Township)
John A. Cimino (D, 2017, Hamilton Township)
Samuel T. Frisby Sr. (D, 2018; Trenton)
Andrew Koontz (D, 2019; Princeton)
Nina D. Melker (D, 2018; Hamilton Township – Appointed to serve an unexpired term)
Melker was appointed in September 2018 following the resignation of Anthony Verrelli (D, Hopewell Township) who was appointed to the New Jersey General Assembly on August 5, 2018.
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). Mercer County's constitutional officers are:
County Clerk Paula Sollami-Covello (D, 2018; Lawrence Township)
Sheriff John A. "Jack" Kemler (D, 2017; Hamilton Township)
Surrogate Diane Gerofsky (D, 2021; Lawrence Township)
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.
Mercer County constitutes Vicinage 7 of the Superior Court of New Jersey. The vicinage is seated at the Mercer County Criminal Courthouse, located at 400 South Warren Street in Trenton. 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. The Assignment Judge for Mercer County is Mary C. Jacobson.
Federal representation
Portions of the 4th and 12th Congressional Districts cover the county.
State representatives
The county is part of the 14th, 15th, and 16th Districts in the New Jersey Legislature.
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.
In the 2004 U.S. presidential election, John Kerry carried Mercer County by a 23.4% margin over George W. Bush, with Kerry carrying the state by 6.7% over Bush. 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.
As of August 1, 2020, there were a total of 249,564 registered voters in Mercer County, of whom 111,016 (44.5%) were registered as Democrats, 38,411 (15.4%) were registered as Republicans and 96,317 (38.6%) were registered as Unaffiliated. There were 3,820 (1.5%) voters registered to other parties.
Transportation
Roads and highways
Mercer County has county routes, state routes, U.S. Routes and Interstates that all pass through. , the county had a total of of roadways, of which were maintained by the local municipality, by Mercer County, by the New Jersey Department of Transportation, by the Delaware River Joint Toll Bridge Commission and by the New Jersey Turnpike Authority.
The county roads that traverse through are County Route 518 (only in the Hopewells), County Route 524, County Route 526, County Route 533, County Route 535, County Route 539, County Route 546, County Route 569, County Route 571 and County Route 583.
The state routes that pass through Mercer are Route 27 (only in Princeton), Route 29, Route 31, Route 33, Route 129, and Route 133 (only in East Windsor). There are three US Routes that pass through Mercer County: U.S. Route 1 (which bisects the county), U.S. Route 130 and U.S. Route 206.
Mercer County houses a few limited access roads, such as Interstate 295, Interstate 195, and the New Jersey Turnpike (Interstate 95). Mercer is the only county in the state that hosts I-95 and both its auxiliary routes. Two turnpike interchanges are located in Mercer: Exit 7A in Robbinsville Township and Exit 8 in East Windsor.
Before 2018, Interstate 95 abruptly ended at the interchange with US 1 in Lawrence Township, and became I-295 south. Signs directed motorists to the continuation of I-95 by using I-295 to I-195 east to the New Jersey Turnpike. This was all due in part to the cancellation of the Somerset Freeway that was supposed to go from Hopewell Township in Mercer County up to Franklin Township in Somerset County.
The section of I-95 west of the US 1 interchange in Lawrence was re-numbered as part of I-295 in March 2018, six months before a direct interchange with Interstate 95 in Pennsylvania and the Pennsylvania Turnpike opened. This planned interchange indirectly prompted another project: the New Jersey Turnpike Authority extended the 'dual-dual' configuration (inner car lanes and outer truck / bus / car lanes) to Interchange 6 in Mansfield Township, Burlington County from its former end at Interchange 8A in Monroe Township, Middlesex County. This widening was completed in early November 2014.
Public transportation
Mercer hosts several NJ Transit stations, including Trenton, Hamilton and Princeton Junction on the Northeast Corridor Line, as well as Princeton on the Princeton Branch. SEPTA provides rail service to Center City Philadelphia from Trenton and West Trenton. Long-distance transportation is provided by Amtrak train service along the Northeast Corridor through the Trenton Transit Center.
NJ Transit's River Line connects Trenton to Camden, with three stations in the county, all within Trenton city limits, at Cass Street, Hamilton Avenue and at the Trenton Transit Center.
Mercer County's only commercial airport, and one of three in the state, is Trenton–Mercer Airport in Ewing Township, which is served by Frontier Airlines, offering nonstop service to and from points nationwide.
Municipalities
thumb|right|400px|Index map of Mercer County municipalities (click to see index)
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Municipalities in Mercer County (with 2010 Census data for population, housing units and area) are:
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.
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.
Collegiate athletics
Mercer County is also home to several college athletic programs.
Mercer County is home to two NCAA DI schools. Rider University competes as the Rider Broncs in the MAAC. For wrestling, Rider is a member of the Eastern Wrestling League. The Princeton Tigers compete in the Ivy League.
The College of New Jersey Lions compete in the NCAA DIII as a member of the New Jersey Athletic Conference and the Eastern College Athletic Conference.
Mercer County Community College competes as the Mercer Vikings as a member of the Garden State Athletic Conference and the National Junior College Athletic Association.