Guilford is a town in New Haven County, Connecticut, United States, that borders Madison, Branford, North Branford and Durham, and is situated on I-95 and the Connecticut coast. The town is part of the South Central Connecticut Planning Region. The population was 22,073 at the 2020 census.

Prior to European colonization, the area that became Guilford was the site of Menunkatuck, a Quinnipiac village. The Quinnipiac spoke Quiripi, one of the Eastern Algonquian branches of the Algonquian language family.

By 1614, the Dutch had surveyed, charted, and established New Netherland, a colonial province, with claimed territories from the Delmarva Peninsula to Cape Cod. This included claims over the Quinnipiac territory. However, a lack of any significant Dutch presence in the area gave English settlers an opportunity to settle in the Quinnipiac territory. Dutch claims over land that included Menunkatuck (and would later include Guilford) remained until the 1674 Treaty of Westminster that ended the Third Anglo-Dutch War.

In June 1637 during the Pequot War, a force of 100 English soldiers and Narragansett, Mohegan, and Montauk allies arrived from Long Island in pursuit of the Pequot grand sachem Sassacus near Menunkatuck. At a neck of land known today as Sachems Head, they captured and executed three Pequot sachems before continuing on west in pursuit of Sassacus.

In 1639, after landing in the plantation of Quinnipiaic (later known as New Haven) via ship from England, a group of 24 English Puritan families led by Rev. Henry Whitfield chose to settle almost 13 miles away near Menukatuck. During their voyage from England, the settlers drafted and signed the Plantation Covenant on June 1, 1639 (O.S.). The text of the covenant is memorialized by an engraved pink granite slab at the corner of Old Whitfield and Whitfield streets. On September 29, 1639 (O.S.), the colonists secured a land grant for their settlement from Shaumpishuh, the female sachem of Menunkatuck.

Guilford was admitted to New Haven Colony in 1643. In 1664, New Haven Colony, including Guilford, joined Connecticut Colony.

The English settlement originally shared the name Menunkatuck with the Quinnipiac village. On July 6, 1643 (O.S.), records of the General Court session held at New Haven note that Menunkatuck changed its name to “Guilforde,” although no reason for the change was recorded. It is assumed that Guilford was named after the town of Guildford, England, the native home of a share of its first English settlers. In early maps of the Connecticut Colony, the town is seen on several maps as "Gilford."

Guilford is considered by some to have the third largest collection of historic homes in New England, with important buildings from the 17th, 18th, and 19th centuries. There are five historic house museums, including Dudley Farm and the Henry Whitfield House (1639), the oldest dwelling house in Connecticut and the oldest stone house built by English settlers in North America. The Comfort Starr House (1695) is one of the oldest wooden framed private dwellings in Connecticut, and one of the few houses remaining of the original signers who settled Guilford.

In June 1781, during the American Revolution, a skirmish was fought on Leete's Island between the Associated Loyalists and local militia under Captain Peter Vail.

According to the United States Census Bureau, the town has a total area of 49.7 square miles (129 km), of which 47.0 square miles (122 km) is land and 2.7 square miles (6.9 km or 5.39%) is water.

The primary settlement in Guilford, known as Guilford Center, is located in the southern part of town around the intersection of U.S. Route 1 and Connecticut Route 77. It is served by three exits of Interstate 95, which passes just north of the town center. The Guilford Center census-designated place had a population of 2,597 at the 2010 census.

The northwest side of Guilford is flanked by the Metacomet Ridge, a mountainous trap rock ridgeline that stretches from Long Island Sound to nearly the Vermont border. Important features of the Metacomet ridge in Guilford include Totoket Mountain; its most notable peak, Bluff Head; and two eastern high points on the Totoket Mountain ridge named East Sugarloaf and West Sugarloaf. The 50-mile (80 km) Mattabesett Trail traverses Bluff Head; a shorter network of trails criss-cross the Sugarloaves. Guilford also contains the Westwoods Trail System which covers 39 miles (63 km) of trails on 1,200 acres (4.9 km) of land.

The Shore Line East train stops at Guilford station with service to Branford, East Haven, New Haven and New London, and the Connecticut Transit S bus travels between Guilford and New Haven several times each day.

• Guilford Center (Guilford Green)
• Leete's Island
• North Guilford
• Nut Plains
• Shell Beach
• Sachem's Head

Other minor communities and geographic features in Guilford are Guilford Lakes, Indian Cove, and Old Quarry.

Historical population

Census	Pop.	Note	%±
1820	4,131		—
1850	2,653		—
1860	2,624		−1.1%
1870	2,576		−1.8%
1880	2,782		8.0%
1890	2,780		−0.1%
1900	2,785		0.2%
1910	3,001		7.8%
1920	2,803		−6.6%
1930	3,117		11.2%
1940	3,544		13.7%
1950	5,092		43.7%
1960	7,913		55.4%
1970	12,033		52.1%
1980	17,375		44.4%
1990	19,848		14.2%
2000	21,398		7.8%
2010	22,375		4.6%
2020	22,073		−1.3%
U.S. Decennial Census

As of the census of 2000, there were 21,398 people, 8,151 households, and 6,039 families residing in the town. The population density was 454.8 inhabitants per square mile (175.6/km). There were 8,724 housing units at an average density of 185.4 per square mile (71.6/km). The racial makeup of the town was 96.04% White, 0.93% African American, 0.05% Native American, 1.65% Asian, 0.41% from other races, and 0.93% from two or more races. Hispanic or Latino of any race were 2.13% of the population.

There were 8,151 households, out of which 35.6% had children under the age of 18 living with them, 64.4% were married couples living together, 7.2% had a female householder with no husband present, and 25.9% were non-families. Of all households 21.6% were made up of individuals, and 8.6% had someone living alone who was 65 years of age or older. The average household size was 2.59 and the average family size was 3.04.

In the town, the population was spread out, with 25.4% under the age of 18, 4.4% from 18 to 24, 26.2% from 25 to 44, 31.2% from 45 to 64, and 12.8% who were 65 years of age or older. The median age was 42 years. For every 100 females, there were 92.8 males. For every 100 females age 18 and over, there were 89.5 males.

The median income for a household in the town was $76,843, and the median income for a family was $87,045 (these figures had risen to $90,026 and $104,852 respectively as of a 2007 estimate). Males had a median income of $60,623 versus $40,307 for females. The per capita income for the town was $37,161. About 2.3% of families and 3.1% of the population were below the poverty line, including 3.4% of those under age 18 and 3.8% of those age 65 or over.

Voter registration and party enrollment as of October 30, 2014
Party		Active voters	Inactive voters	Total voters	Percentage
	Democratic	4,743	551	5,294	33.05%
	Republican	3,183	333	3,516	21.95%
	Unaffiliated	5,995	1113	7,108	44.38%
	Minor parties	94	5	99	0.62%
Total		14,015	2,002	16,017	100%

In the 2008 presidential election, Democrat Barack Obama received 61.02% of the town vote, against 38.06% for Republican John McCain. In 2016, Democrat Hillary Clinton carried the town with 59.2% over Republican Donald Trump with 37.1%.

American Cruise Lines has its headquarters in Guilford. There are many small businesses throughout the town, including the shops on the Guilford Green.

Guilford is served by the Guilford Public Schools district, which provides comprehensive education from kindergarten through high school. The district comprises four elementary schools, two middle schools, and a high school, offering a range of academic and extracurricular programs.

• Elementary Schools: Guilford has four elementary schools: Calvin Leete Elementary School, A.W. Cox Elementary School, Melissa Jones Elementary School, and Guilford Lakes Elementary School.

• Middle Schools: Baldwin Middle School serves students in grades five through six. Adams Middle School serves students in grades seven through eight.

• High School: Guilford High School, serving grades nine through twelve, offers a wide array of academic courses, including Advanced Placement (AP) classes and college preparatory programs.

The Guilford Free Library is a resource for the community, providing access to a vast collection of books, digital media, historical materials about Guilford’s history and genealogy, and educational programs for all ages. The library hosts numerous events, workshops, and activities aimed at promoting literacy and lifelong learning.

The town government operates these parks:

• Bittner Park: 123 acres (0.50 km) of woodlands and 15 acres (61,000 m) of playground, a lighted softball field (Cash Mitchell Field), baseball and soccer fields, jogging/walking path; trout trail; roller sports complex with a skate park, roller hockey and roller blading. Ice skating available in winter.
• Chaffinch Island: Picnic areas, short walking trails, salt marsh.
• Chittenden Park: Softball and soccer fields, bocce courts, picnicking, unsupervised beach area
• Jacobs Beach: Public swimming (salt water), playground, volleyball courts, picnicking; nonresidents may use the beach, but are charged a daily fee at the gate.
• Lake Quonnipaug: Public swimming (fresh water), picnic area, small craft launch.
• Long Hill: 8-acre (32,000 m) park with playing fields for baseball, football, soccer/lacrosse and field hockey
• Mill Pond: Lighted, supervised ice skating in winter; fishing
• Nut Plains: Lacrosse/soccer field
• Town Green: available for special events

Guilford, Connecticut is noted for its rolling farmland, its avoidance of the density and sprawl that has occurred from land use regulations of its neighboring communities, and its numerous historic homes and sites.

• Bishop's Orchards
• Guilford Green
• Rothberg Institute For Childhood Diseases
• Westwoods Trails: conservation area managed by the Guilford Land Conservation Trust

The town is home to one of the most well-preserved and intact central villages in the region. Its historical significance is further underscored by the presence of over 450 historical houses dating from the 17th to the 19th centuries.

Among its notable designations, Guilford includes a National Historic Landmark, four designated areas, and 11 individual structures listed on the National Register of Historic Places. Additionally, the town features two local historic districts encompassing a total of 226 buildings within the downtown area, highlighting its rich historical and architectural legacy.

Building	Image	First built	National Register of Historic Places listed	Current use	Notes
Henry Whitfield House		1639	Yes	House museum	Oldest house in Connecticut and the oldest stone house in New England.
Acadian House		1670	Yes	Residential	One of Connecticut's oldest surviving houses. Notable for its later occupation by refugee Acadians following their 1755 deportation from Nova Scotia.
Elisha Pitkin House		1690	Yes	Residential	Moved to Guilford from East Hartford in 1955
Comfort Starr House		1695	No	Residential	Classic New England saltbox home.
Pelatiah Leete House		1710	Yes	Residential	Oldest surviving house associated with the locally prominent Leete family, who were among the founders of New Haven Colony.
Hyland House		1713	Yes	House museum	Open to the public as a museum since 1918.
Jared Eliot House		1723	Yes	Residential	Well-preserved example of period residential architecture
Thomas Burgis II House		1735	Yes	Residential	One of Guilford's finest and best-documented colonial-era houses
Sabbathday House		1735	Yes	Residential	One of two Sabbathday houses to survive in the town. Built for the purpose of sheltering church-going families between morning and afternoon services.
Griswold House		1764	Yes	House museum	Museum includes the saltbox house, a historic blacksmith shop, a barn with farm tools and implements, two corn cribs and a Victorian era three seat outhouse.
Falkner Island Light		1802	Yes	Lighthouse	Second-oldest extant lighthouse in Connecticut. Commissioned by Thomas Jefferson.
Medad Stone Tavern		1803	Yes	House museum	Example of early 19th-century Federal period architecture. Never used as a tavern.
First Congregational Church		1830	No	Church	Third church building for a congregation founded in 1643.

Historic districts include:

• Guilford Historic Town Center
• Dudleytown Historic District
• Meeting House Hill Historic District (North Guilford)
• Route 146 Historic District (Branford and Guilford)

Building	Image	Built	Current use	Notes
Junior Olsen House		1951	Residential	Modernist home by sculptor and architectural designer Tony Smith. Old Quarry neighborhood.
Fred Olsen, Sr. House		1953	Residential	Modernist residential compound by sculptor and architectural designer Tony Smith. Old Quarry neighborhood.
"The spaceship"		1987	Condos	Uniqiue condo building designed by architect Wilfred J. O. Armster.

• Wilfred J. O. Armster. (1938–2019), architect
• Humbert Allen Astredo (1929–2016), American stage, film, and television actor best known for the numerous roles he performed on the daytime Gothic horror soap opera Dark Shadows, most notably that of the warlock Nicholas Blair
• Abraham Baldwin (1754–1807), minister, patriot, politician, and founding father
• Robert Elliott De Forest (1845–1924), Democratic member of the United States House of Representatives, mayor of Bridgeport, Connecticut, member of the Connecticut Senate and Connecticut House of Representatives, born in Guilford
• Ronald Duman (1954–2020), neuroscientist died in Guilford
• Moses Gunn (1929–1993), American actor, resided in Guilford since the 1970s
• Fitz-Greene Halleck (1790–1867), American poet and author
• Samuel Johnson (1696-1772), American colonial intellectual and educator; first president of King's College (now Columbia University)
• Samuel Johnson Jun'r (1757–1836), schoolmaster and teacher of Fitz-Greene Halleck; as the compiler of A School Dictionary (1798), the first American lexicographer
• Edward Ruggles Landon (1813–1883), Connecticut politician
• William Leete (c. 1612–1683), Guilford town clerk, justice of the peace, Governor of the New Haven Colony (1661-1665), and Governor of the Colony of Connecticut (1676-1683)
• Leonard C. Lewin (1916–1999), author of The Report from Iron Mountain
• Frank Modell (1917–2016), cartoonist, died in Guilford
• Aldo Parisot (1918–2018), Brazilian-born American cellist and cello teacher
• Lavinia Stoddard (1787–1820), poet, school founder
• Shaumpishuh (d. 1686), sachem of Menunkatuck
• Henry Whitfield (c.1590-c.1657), Guilford founder and Puritan minister

• Jeffrey Ambroziak, cartographer, inventor, and attorney
• Jamie Arentzen (b. 1970), American guitarist, musician; member of various rock bands including Sky Heroes, American Hi-Fi, Dream Club
• Thom Brooks, political and legal philosopher
• Benjamin Chan, American scientist at Yale University
• Mickey Curry, Drummer for Bryan Adams
• David DeMille, physicist and Professor of Physics at University of Chicago.
• Joe Flood, musician and songwriter
• Nick Fradiani (b. 1985), American Idol season 14 winner, born in Guilford
• Timothy Mellon, heir
• Becki Newton, actress in Ugly Betty and How I Met Your Mother, grew up in Guilford and is a Guilford High School Alumna
• David Allen Sibley, ornithologist, author, and illustrator
• Jennifer Westfeldt, actress and screenwriter known for Kissing Jessica Stein, born in Guilford
• Carl Zimmer, science writer

• Connecticut portal

• "Deed from Shaumpishuh (Squa Sachem) and Quassaquench to Rev. Henry Whitfield and others, 23 August 1639 - 29 September 1639". Massachusetts Historical Society. Retrieved August 14, 2024.
• "Manuscript map of lands of Quinnipiac sachems along the Connecticut shoreline and articles of agreement between Rev. Henry Whitfield and others, and Shaumpishuh (Squa Sachem) and Quassaquench and others, 23 August 1639 - 29 September 1639". Massachusetts Historical Society. Retrieved August 14, 2024.
• Steiner, Bernard Christian (1897). History of the Plantation of Manunkatuck and of the Original Town of Guilford, Connecticut. Retrieved August 14, 2024.

• Town of Guilford official website
• Guilford Keeping Society
• Guilford Preservation Alliance
• Guilford Free Library
• Guilford Public Schools Archived July 7, 2005, at the Wayback Machine
• Guilford Chamber of Commerce Archived April 10, 2007, at the Wayback Machine
• Guilford, Connecticut at City-Data.com