New Haven in the U.S. state of Connecticut, is the principal municipality in Greater New Haven. It is the second-largest city in Connecticut. It was founded in 1638 by English Puritans, and a year later eight streets were laid out in a four-by-four grid, creating what is now commonly known as the "Nine Square Plan", now recognized by the American Institute of Certified Planners as a National Planning Landmark. The central common block is New Haven Green, a 16-acre (6 ha) square, now a National Historic Landmark and the center of Downtown New Haven.

New Haven is the home of Yale University. The university is an integral part of the city's economy, being New Haven's biggest taxpayer and employer. Health care (hospitals and biotechnology), professional services (legal, architectural, marketing, and engineering), financial services, and retail trade also help to form an economic base for the city.

New Haven had the first public tree planting program in America, producing a canopy of mature trees (including some large elms) that gave New Haven the nickname "The Elm City".