PHILADELPHIA COUNTY, situated in the southeast part of Pennsylvania, with Delaware river on the southeast, and traversed by the Schuylkill. Area, 128 square miles. Face of the, undulating; soil, good. Seat of justice, Philadelphia. Pop. in 1810, 111,210; in 1820, 137,097; in 1830, 188,777; in 1840, 258,037; in 1850, 408,762. (Fanning's, 1853)