What may have started as a single farm, expanded substantially by the installing of 2 pits named: 'Margret' or 'Peggy', sunk in the 18th c.; and 'Dorethea' or 'Dolly', sunk in the 1810s. by 1821 the population had risen to 2,306.[4] In 1816 the town was described by Robert Surtees, as follows:
A little to the North of Newbottle, below the brow of the hill, lies Philadelphia-Row, one of those settlements provided by the coal-owners for their workmen, who live here as a distinct class in society, almost entirely separated from the agricultural part of the community. These colonies form at every point the strongest contrast to the varied and picturesque appearance of the genuine village—consisting, in general, of long uniform lines of low brick buildings, running along each side of a public road, black with coal-dust.
— Robert Surtees, The history and antiquities of the County Palatine of Durham (1816)[4][5]
Philadelphia was the place of the 1815 Philadelphia train accident, the explosion of the boiler of an early steam locomotive. The number of deaths (16, other sources state 13) was the highest in a railway accident until 1842.[6][7]
