Suffolk County ( SUF-ək) is the easternmost county in the U.S. state of New York, constituting the eastern two-thirds of Long Island. Suffolk is bordered to its west by Nassau County, to its east by Gardiners Bay and the open Atlantic Ocean, to its north by Long Island Sound, and to its south by the Atlantic Ocean.
As of the 2020 United States census, Suffolk County's population was 1,525,920, its highest decennial count ever, making Suffolk the fourth-most populous county in the State of New York and the most populous outside of the boroughs of New York City. Its county seat is Riverhead, though most county offices are in Hauppauge. The county was named after the county of Suffolk in England, the origin of its earliest European settlers.
Suffolk County incorporates the easternmost extreme of both the New York City metropolitan area and New York State. The geographically largest of Long Island's four counties and the second-largest of New York's 62 counties, Suffolk County is 86 miles (138 km) in length and 26 miles (42 km) in width at its widest (including water). Most of the island is near sea level, with over 1,000 miles (1,600 kilometers) of coastline.
Like other parts of Long Island, the county's high population density and proximity to New York City has resulted in a diverse economy, including industry, science, agriculture, fishery, and tourism. Major scientific research facilities in Suffolk County include Brookhaven National Laboratory in Upton and Plum Island Animal Disease Center on Plum Island. The county is home to Stony Brook University in Stony Brook and Farmingdale State College in East Farmingdale.
Contents
History
Suffolk County was part of the Connecticut Colony before becoming an original county of the province of New York, one of twelve created in 1683. From 1664 until 1683, it had been the East Riding of Yorkshire. Its boundaries were essentially the same as at present, with only minor changes in the boundary with its western neighbor, which was originally Queens County but has been Nassau County since the separation of Nassau from Queens in 1899.
During the American Revolutionary War, Great Britain occupied Suffolk County after the retreat of George Washington's forces in the Battle of Long Island, and the county remained under occupation until the British evacuation of New York on November 25, 1783.
According to the Suffolk County website, the county is the leading agricultural county in the state of New York, saying that: "The weather is temperate, clean water is abundant, and the soil is so good that Suffolk is the leading agricultural county in New York State. That Suffolk is still number one in farming, even with the development that has taken place, is a tribute to thoughtful planning, along with the excellent soil, favorable weather conditions, and the work of the dedicated farmers in this region."
Geography
According to the U.S. Census Bureau, the county has an area of 2,373 square miles (6,150 km2), of which 912 square miles (2,360 km2) is land and 1,461 square miles (3,780 km2) (62%) is water. It is the second-largest county in New York by total area and occupies 66% of the land area of Long Island.
Suffolk County occupies the central and eastern part of Long Island, in the extreme east of the State of New York. The eastern end of the county splits into two peninsulas, known as the North Fork and the South Fork. The county is surrounded by water on three sides, including the Atlantic Ocean and Long Island Sound, with 980 miles (1,580 km) of coastline. The eastern end contains large bays.
The highest elevation in the county, and on Long Island as a whole, is Jayne's Hill in West Hills, at 401 feet (122 m) above sea level. This low lying-geography means that much of the county is vulnerable to sea level rise.
Climate
Suffolk County sits at the convergence of climate zones including the humid continental (Dfa) and humid subtropical (Cfa), bordering closely on an oceanic climate (Cfb). The majority of the county by land area is in the Dfa zone. Summers are cooler at the east end than in the western part of the county. The hardiness zone is 7a, except in Copiague Harbor, Lindenhurst, and Montauk, where it is 7b. Average monthly temperatures in Hauppauge range from 31.0 °F (−0.6 °C) in January to 74.0 °F (23.3 °C) in July, and in the Riverhead town center they range from 30.1 °F (−1.1 °C) in January to 72.8 °F (22.7 °C) in July, which includes both daytime and nighttime temperatures. On February 23, 2026, Central Islip in Suffolk County was besieged by 31 inches of snow, making it the largest single-day snowfall on record in Suffolk.
Adjacent counties
Suffolk County has maritime boundaries with five other U.S. counties and is connected by land only to Nassau County.
Nassau County—west
Fairfield County, Connecticut—northwest
New Haven County, Connecticut—north
Middlesex County, Connecticut—north
New London County, Connecticut—north
Washington County, Rhode Island—northeast
National protected areas
Amagansett National Wildlife Refuge
Conscience Point National Wildlife Refuge
Elizabeth A. Morton National Wildlife Refuge
Fire Island National Seashore
Sayville National Wildlife Refuge
Seatuck National Wildlife Refuge
Target Rock National Wildlife Refuge
Wertheim National Wildlife Refuge
Demographics
2010 census
According to the 2010 U.S. census there were 1,493,350 people and 569,985 households residing in the county. The census estimated Suffolk County's population decreased slightly to 1,481,093 in 2018, representing 7.5% of the census-estimated New York State population of 19,745,289 and 19.0% of the census-estimated Long Island population of 7,869,820. The population density in 2010 was 1,637 people per square mile (632 people/km2), with 569,985 households at an average density of 625 per square mile (241/km2). However, by 2012, with an estimated total population increasing moderately to 1,499,273 there were 569,359 housing units. As of 2006, Suffolk County was the 21st-most populous county in the United States.
By 2014, the county's racial makeup was estimated at 85.2% White, 8.3% African American, 0.6% Native American, 4.0% Asian, 0.1% Pacific Islander, and 1.8% from two or more races. Those identifying as Hispanic or Latino, of any race, were 18.2% of the population. Those who identified as "white alone", not being of Hispanic or Latino origin, represented 69.3% of the population. In 2006, the county's racial or ethnic makeup was 83.6% White (75.4% White Non-Hispanic). African Americans were 7.4% of the population. Asians stood at 3.4% of the population. 5.4% were of other or mixed race. Latinos were 13.0% of the population. In 2007, Suffolk County's most common ethnicities were Italian (29.5%), Irish (24.0%), and German (17.6%).
In 2002, The New York Times cited a study by the non-profit group ERASE Racism, which determined Suffolk and its neighboring county, Nassau, to be the most racially segregated suburbs in the United States.
In 2006, there were 469,299 households, of which 37.00% had children under the age of 18 living with them, 62.00% were married couples living together, 10.80% had a female householder with no husband present, and 23.20% were non-families. 18.30% of all households were made up of individuals, and 7.80% had someone living alone who was 65 years of age or older. The average household size was 2.96 and the average family size was 3.36.
In the county, the population was spread out, with 26.10% under the age of 18, 7.60% from 18 to 24, 31.20% from 25 to 44, 23.30% from 45 to 64, and 11.80% who were 65 years of age or older. The median age was 36 years. For every 100 females, there were 95.90 males. For every 100 females age 18 and over, there were 92.80 males.
Law and government
United States Senate
In 2003, Democrat Steve Levy was elected county executive, ending longtime Republican control. In 2001, Democrat Thomas Spota was elected District Attorney, and ran unopposed in 2005. Although Suffolk voters gave George H. W. Bush a victory here in 1992, the county voted for Bill Clinton in 1996 and continued the trend by giving Al Gore an 11-percent victory in the county in 2000. 2004 Democratic candidate John Kerry won by a much smaller margin of under one percent, in 2008 Democratic candidate Barack Obama won by a slightly larger 6 percent margin, 52.5%-46.5%. In 2012, he carried the county by a slightly smaller margin 51%-47%. In 2016, Republican candidate Donald Trump won Suffolk County by a 6.9 percent margin, becoming the first Republican to carry the county since 1992. In 2020, Trump again won Suffolk County; this time, however, it was decided by just 232 votes out of nearly 800,000 votes cast, making it the closest county in the nation in terms of percentage margin, and representing nearly a seven-point swing towards the Democratic ticket of former Vice President Joe Biden and junior California senator Kamala Harris. In percentage terms, it was the closest county in the state, although Ontario County and Warren County had narrower raw vote margins of just 33 and 57 votes, respectively. Suffolk was one of five counties in the state that Trump won by less than 500 votes. With Tarrant County, Texas and Maricopa County, Arizona flipping Democratic in 2020, Suffolk County was the most populous county in the nation to vote for Trump in 2020. In 2024, Trump won 54% of the vote in Suffolk county, the highest percentage since 1988.
As a whole, both Suffolk and Nassau counties are considered swing counties. However, until 2016, they tended not to receive significant attention from presidential candidates, as the state of New York has turned reliably Democratic at the national level. In 2008 and 2012, Hofstra University in Nassau County hosted a presidential debate. Hofstra hosted the first debate of the 2016 presidential election season, on September 26, 2016, making Hofstra the first college or university in the United States to host a presidential debate in three consecutive elections. The presence on the 2016 ticket of Westchester County resident Hillary Clinton and Manhattan resident Donald Trump resulted in greater attention by the candidates to the concerns of Long Island. Trump visited Long Island voters and donors at least four times while Clinton made one stop for voters and one additional stop in the Hamptons for donors.
After the 2022 midterm election results were counted, Suffolk appears to have moved further to the right. Republican gubernatorial candidate and Suffolk County native Lee Zeldin won the county by more than 17 points over the Democratic candidate Kathy Hochul. Republicans, as of 2024, hold both congressional districts covering that being New York's 1st congressional district represented by Nick LaLota and New York's 2nd congressional district represented by Andrew Garbarino.
Suffolk County Executives
* Appointed to complete Cohalan's term.
** Levy was originally elected as a Democrat, but became a Republican in 2010.
Suffolk County Legislature
The county has 18 legislative districts, each represented by a legislator. As of 2026, there are 9 Republicans, 7 Democrats, and 2 Conservatives.
Republicans controlled the county legislature until a landmark election in November 2005 where three Republican seats switched to the Democrats, giving them control. In November 2007, the Democratic Party once again retained control over the Suffolk County Legislature, picking up one seat in the process. In November 2009, the Republican Party regained the seat lost in 2007 but remained in the minority for the 2010-2011 session. In November 2011, the Democratic Party maintained control over the Suffolk County Legislature picking up one seat that had been held by an Independence Party member. In November 2013, the Republican Party gained the 14th district seat, but remained in the minority until 2021, when the GOP flipped the county legislature, picking up three seats with incumbents Robert Calarco (the sitting Presiding Officer) and Susan Berland (the sitting Majority Leader) losing their bids for re-election. The Suffolk GOP built on these gains in the 2023 general election, gaining a 12-6 supermajority.
Law enforcement
Police services in the five western towns (Babylon, Huntington, Islip, Smithtown and Brookhaven) are provided primarily by the Suffolk County Police Department. The five "East End" towns (Riverhead, Southold, Shelter Island, East Hampton, and Southampton), maintain their own police and other law enforcement agencies. Also, there are a number of villages, such as Amityville, Asharoken, Lloyd Harbor, Northport, and Westhampton Beach that maintain their own police forces. In 1994, the Village of Greenport voted to abolish its police department and turn responsibility for law and order over to the Southold police department.
After the Long Island State Parkway Police was disbanded in 1980, all state parkways in Suffolk County became the responsibility of Troop L of the New York State Police, headquartered at Republic Airport. State parks, such as Robert Moses State Park, are the responsibility of the New York State Park Police, based at Belmont Lake State Park. In 1996, the Long Island Rail Road Police Department was consolidated into the Metropolitan Transportation Authority Police, which has jurisdiction over all rail lines in the county. Since the New York state legislature created the New York State University Police in 1999, they are in charge of all law enforcement services for State University of New York property and campuses. The State University Police have jurisdiction in Suffolk County at Stony Brook University and Farmingdale State College.
The Suffolk County Sheriff's Office is a separate agency. The sheriff, an elected official who serves a four-year term, operates the two Suffolk County correctional facilities (in Yaphank and Riverhead), provides county courthouse security and detention, service and enforcement of civil papers, evictions and warrants. The Sheriff's Office is also responsible for securing all county-owned property, such as county government office buildings, as well as the campuses of the Suffolk County Community College. As of 2008, the Suffolk County Sheriff's Office employed 275 Deputy Sheriffs, 850 corrections officers, and about 200 civilian staff.
Suffolk County has a long maritime history with several outer barrier beaches and hundreds of square miles of waterways. The Suffolk Police Marine Bureau patrols the 500 square miles (1,000 km2) of navigable waterways within the police district, from the Connecticut and Rhode Island state line which bisects Long Island Sound to the New York state line 3 miles (5 km) south of Fire Island in the Atlantic Ocean. Some Suffolk County towns (Islip, Brookhaven, Southampton, East Hampton, Babylon, Huntington, Smithtown) also employ various bay constables and other local marine patrol, which are sworn armed peace officers with full arrest powers, providing back up to the Suffolk Police Marine Bureau as well as the United States Coast Guard.
Courts
Suffolk County is part of the 10th Judicial District of the New York State Unified Court System; is home to the Alfonse M. D'Amato Courthouse of the Federal U.S. District Court, Eastern District of New York; and has various local municipal courts. The State Courts are divided into Supreme Court, which has general jurisdiction over all cases, and lower courts that either hear claims of a limited dollar amount, or of a specific nature. Similarly, the local courts hear claims of a limited dollar amount, or hear specific types of cases. The Federal Court has jurisdiction over Federal Claims, State Law claims that are joined with Federal claims, and claims where there is a diversity of citizenship.
The Suffolk County Supreme Court is a trial court of unlimited general original jurisdiction (except as to matters which the federal courts have exclusive jurisdiction), but it generally only hears cases that are outside the subject-matter jurisdiction of other trial courts of more limited jurisdiction. The Suffolk County Clerk is the Clerk of the Court of the Supreme Court.
The main courthouse for the Supreme Court is in Riverhead, which has been the court's home since 1729. The original courthouse was replaced in 1855, and that courthouse was expanded in 1881. The courthouse was damaged by fire and rebuilt in 1929. In 1994, a new court building was added to the complex. This Courthouse was dedicated as the "Alan D. Oshrin Supreme Court Building" on August 1, 2011.
The Supreme Court also shares space in the Cohalan Court Complex in Central Islip with several other courts and county agencies. Matrimonial actions are heard in the Supreme Court, and those matters are generally heard in the Supreme Court section of the Cohalan Court Complex.
The Suffolk County Court is a trial court of limited jurisdiction. It has jurisdiction over all of Suffolk County, and is authorized to handle criminal prosecutions of both felonies and lesser offenses committed within the county, although in practice most minor offenses are handled by the local courts. It is the trial court for felonies, or where a person is indicted by a Grand Jury in Suffolk County. The County Court also has limited jurisdiction in civil cases, generally involving amounts up to $25,000. The County Court is in the Cromarty Court Complex Criminal Courts Building in Riverhead.
Education
Colleges and universities
State University of New York
Stony Brook University in Stony Brook with a satellite campus in Southampton
Farmingdale State College in East Farmingdale
Suffolk County Community College in Selden, Riverhead, and Brentwood, satellite centers in Sayville and Riverhead
Private
Five Towns College in Dix Hills
St. Joseph's University in Patchogue
Touro University System with its School of Health Sciences in Central Islip and its Law Center in Central Islip
Cold Spring Harbor Laboratory School of Biological Sciences in Cold Spring Harbor
Satellite and branch campuses
Adelphi University in Hauppauge
Long Island University in Brentwood and Riverhead, on the campuses of Suffolk County Community College
Molloy University in Amityville
School districts
School districts (all officially designated for grades K-12) include:
Media
Television stations
WFTY-DT, Smithtown
WLNY-TV, Riverhead
WVVH-CD, Southampton
Suffolk seashore
Fire Island Lighthouse was an important landmark for many trans-Atlantic ships coming into New York Harbor in the early 20th century. For many European immigrants, the Fire Island Light was their first sight of land upon arrival in America.
The Fire Island Inlet span of the Robert Moses Causeway connects to Robert Moses State Park on the western tip of Fire Island.
The Great South Bay Bridge, the first causeway bridge, had only one northbound and one southbound lane, was opened to traffic in April 1954. The span of 2 miles (3 km) across Great South Bay to Captree Island features a main span of 600 feet (200 m), with a clearance for boats of 60 feet (20 m).
After crossing the State Boat Channel over its 665-foot-long (203 m) bascule bridge, the causeway meets the Ocean Parkway at a cloverleaf interchange. This interchange provides access to Captree State Park, Gilgo State Park and Jones Beach State Park.
The Fire Island Inlet Bridge continues the two-lane road, one lane in each direction, across Fire Island Inlet to its terminus at Robert Moses State Park and The Fire Island Lighthouse. Robert Moses Causeway opened in 1964.
Suffolk County has the most lighthouses of any United States county, with 15 of its original 26 lighthouses still standing. Of these 15, eight are in Southold township alone, giving it more lighthouses than any other township in the United States.
Secessionist movements
At various times, there have been proposals for a division of Suffolk County into two counties. The western portion would be called Suffolk County, while the eastern portion of the current Suffolk County would comprise a new county to be called Peconic County. Peconic County would consist of the five easternmost towns of Suffolk County: East Hampton, Riverhead, Shelter Island, Southampton and Southold, plus the Shinnecock Indian Reservation.
The proposed Peconic County flag showed the two forks at the east end of Long Island separated by Peconic Bay. The star on the north represents Southold. The stars on the South Fork represent Southampton and East Hampton. Riverhead is at the fork mouth and Shelter Island is between the forks. The secessionist movement has not been active since 1998.
The End of the Hamptons: Scenes from the Class Struggle in America's Paradise, by Corey Dolgon (New York University Press, 2005) examined the class roots of the secessionist movement in the Hamptons. In his review, Howard Zinn wrote that the book "[t]akes us beyond the much-romanticized beaches of Long Island to the rich entrepreneurs and their McMansions, the Latino workers, and the stubborn indigenous residents refusing to disappear. The book is important because it is in so many ways a microcosm of the nation." The book won the Association for Humanist Sociology's 2005 Book Prize and the American Sociological Association's Marxist Section Book Award in 2007.
Finance and taxation
Suffolk County has an 8.625% sales tax, compared to an overall New York State sales tax of 4%, consisting of an additional 4.25% on top of the state and MTA assessment of .375%
Health
In March 2020, the COVID-19 pandemic first affected the county. As of December 12, 2020, there have been a total of 73,281 cases and 2,153 deaths from the virus.
Hospitals
Tertiary care hospitals:
Good Samaritan University Hospital
South Shore University Hospital
Stony Brook University Hospital
Community hospitals:
Huntington Hospital
Mather Hospital
NYU Langone Hospital — Suffolk
Peconic Bay Medical Center
Stony Brook Eastern Long Island Hospital
Stony Brook Southampton Hospital
St. Charles Hospital
Saint Catherine of Siena Medical Center
Specialty care hospitals:
South Oaks Hospital
Stony Brook Children's Hospital
Communities
In the State of New York, a town is the major subdivision of each county. Towns provide or arrange for most municipal services for residents of hamlets and selected services for residents of villages. All residents of New York who do not live in a city or on an Indian reservation live in a town. A village is an incorporated area which is usually, but not always, within a single town. A village is a clearly defined municipality that provides the services closest to the residents, such as garbage collection, street and highway maintenance, street lighting and building codes. Some villages provide their own police and other optional services. A hamlet is an informally defined populated area within a town that is not part of a village.
Figures in parentheses are 2022 population estimates from the Census Bureau.
Gardiners Island
Gardiners Island is an island off eastern Suffolk County. The Island is 6 miles (10 km) long, and 3 miles (5 km) wide and has 27 miles (43 km) of coastline. The same family has owned the Island for nearly 400 years; one of the largest privately owned islands in America or the world. In addition, it is the only American real estate still intact as part of an original royal grant from the English Crown.
Robins Island
Robins Island is an Island in the Peconic Bay between the North and South folks of eastern Suffolk County. It is within the jurisdiction of Town of Southold in Suffolk County, New York. The Island is 435 acres (1.8 km2) and presently undeveloped. The island is privately owned and not accessible to the public.
Indian reservations
Two Indian reservations are within the borders of Suffolk County:
Shinnecock Reservation
Poospatuck Reservation
Transportation
The county includes a lot of roadways and other public transportation infrastructure. The local Suffolk County Legislature oversees funding and regulations for the infrastructure. In 2019, the legislature required all new projects to account for future climate change caused sea level rise.
Major highways
I-495 (Long Island Expressway) traverses the county from the Nassau County line in the West to Riverhead in the East. Original plans called for the Expressway to extend further past Riverhead and along the island's North Fork, possibly to Orient Point, where a crossing to Connecticut could be built. The expressway connects to Manhattan via the Queens-Midtown Tunnel.
New York State Route 27 crosses the county from the Nassau County line in the West to Montauk Point in the East, which is also the easternmost point in the State of New York. The road is limited-access from West Babylon to Southampton.
Airports
Commercial airport:
Long Island MacArthur Airport (ISP/KISP)
General aviation airports:
Republic Airport (FRG/KFRG)
Brookhaven Calabro Airport (WSH/KHWV/HWV)
Francis S. Gabreski Airport (FOK/KFOK)
Town of East Hampton Airport (JPX/KJPX)
Elizabeth Field (Fisher's Island) (FID/0B8)
Public transportation
Suffolk County is served by Suffolk County Transit. Long Island Rail Road, the Hampton Jitney, and Hampton Luxury Liner connect Suffolk County to New York City. Some parts of Suffolk County are also served by NICE bus.
Notable people
Craig Biggio
Jimmy Buffett
Mariah Carey
Mick Foley
Kevin James
Loudon Wainwright III
Carl Yastrzemski
Billy Joel

