Darby is a borough in Delaware County, Pennsylvania, United States, along Darby Creek 5 miles (8.0 km) southwest of Center City, Philadelphia. Darby Borough is distinct from the nearby municipality of Darby Township.
Darby was settled in 1682 by seven Quaker families led by abolitionist & fair trade avocate John Blunston. The name Darby is derived from the English city of Derby (pronounced "Darby"), the county town of Derbyshire (pronounced "Darbyshire"), the origin of many early settlers. Incorporated on May 3, 1853, it had 3,429 residents in 1900, 6,305 in 1910, 10,334 in 1940, and 10,687 at the 2010 census.
Darby founder John Blunston immigrated to Pennsylvania in October 1682. He was involved in real estate, agriculture, and goods trading. An early Quaker settler, Blunston was a close associate of William Penn and an active political figure in early Pennsylvania. He first served in the Colonial Assembly from 1683 to 1688. In this early stage of provincial government, Blunston became a strong proponent for the rights of the Assembly.