The city served as co-capital of Connecticut from 1701 until 1873, when sole governance was transferred to the more centrally located city of Hartford.

Benedict Arnold established himself in New Haven as a pharmacist and bookseller in 1762. He later fought with distinction for the American Continental Army, rising to the rank of major general before plotting to surrender West Point to British forces. The plot was discovered in September 1780, and he fled to the British lines.

New Haven has a history of professional sports franchises dating back to the 19th century and has been the home to professional baseball, basketball, football, hockey, and soccer teams--including the New York Giants of the National Football League, who played at the Yale Bowl from 1973 to 1974.

"Peace Frog" features lines inspired by true events surrounding the band's frontman Jim Morrison, including "Blood in the streets in the town of New Haven," which references Morrison's onstage arrest for "attempting to incite a riot" on December 9, 1967, during a live performance in New Haven Arena.

The city struck fortune in the late 18th century with the inventions and industrial activity of Eli Whitney, a Yale graduate who remained in New Haven to develop the cotton gin and establish a gun-manufacturing factory in the northern part of the city near the Hamden town line. It was in Whitney's gun-manufacturing plant that Samuel Colt invented the automatic revolver in 1836. That area is still known as Whitneyville, and the main road through both towns is known as Whitney Avenue.

The city is drained by three rivers: the West, Mill, and Quinnipiac. The West River discharges into West Haven Harbor, while the Mill and Quinnipiac rivers discharge into New Haven Harbor.

In 1661, the Regicides who had signed the death warrant of Charles I of England were pursued by Charles II. Two of them, Colonel Edward Whalley and Colonel William Goffe, fled to New Haven for refuge. City founder John Davenport arranged for them to hide in the West Rock hills northwest of the town. They were later joined by a third judge, John Dixwell. Most New Haveners refer to these men as "The Three Judges".

Today, roughly half the populations of East Haven, West Haven, and North Haven are Italian-American.