East Granby is a town in Hartford County, Connecticut, United States. The population was 5,148 at the 2010 census.
Original inhabitants of the current East Granby area were Native American peoples, including the Algonquin/Poquonock, the Massaco, and the Agawam.
The East Granby area was first settled by Europeans in 1664, which was one of the four Congregational parishes in Simsbury. The Turkey Hills Ecclesiastical Society in 1786 became a section of Granby, and in 1858 was incorporated as the Town of East Granby.
The first incorporated copper mine in America resided in what is now East Granby. The mine later became Old Newgate Prison, a Revolutionary War jail and the first state prison in the United States (1790).
Farming was the mainstay of the town for much of its history. The early twentieth century saw local farmers specializing in dairy product and tobacco.
East Granby experienced a housing boom that started in 1951 and resulted in a rise in population.
The town celebrated its 150th anniversary with a three-day festival June 7–9, 2008.
East Granby is in the Farmington valley, with the Farmington River passing along the southern border of the town. The Metacomet Ridge, a mountainous trap rock ridgeline that stretches from Long Island Sound to nearly the Vermont border, runs through the center of the town, cutting off Salisbury Plain to the east, which used to lie under the ancient, glacial Lake Hitchcock.