CHESTER, a city of Delaware county, Pennsylvania, U.S.A., on the Delaware river, 13m. S.W. of Philadelphia. It is on Fed eral highway 13, and is served by the Baltimore and Ohio, the Pennsylvania and the Reading railways. The population in 1920 was 58,030, of whom 11,292 were foreign-born white and 7,125 were negroes; and was 59,164 in 1930 Federal census. Chester has a good harbour, with considerable commerce. It has one of the largest shipbuilding yards in the United States, a Ford assembly and shipping plant and eight large steel-casting plants. Other manufactures of importance are cotton, silk and woollen goods, paper, plaster, iron, cutlery, lace, hosiery and steel tubing. The total factory output in 1925 was valued at $70,557,135. The assessed valuation of property in 5927 was $67,903,696. On the edge of the city is Crozer Theological seminary (Baptist), founded in by the family of John P. Crozer Settled about 1645 by the Swedes, who called it Upland, Chester is the oldest town in Pennsylvania. It was the seat of the Swedish courts until 1682, when William Penn arrived. The spot where he landed is marked by a memorial stone, and the house he occu pied for a time (built in 1683) still stands. The old city hall (1724) is one of the oldest public buildings in the country. After the battle of Brandywine Washington retreated to Chester, and here wrote his account of the battle. Soon after that it was occu pied by the British. It was incorporated as a borough in 1701, and received a city charter in 1866. Its period of rapid growth began with the introduction of large manufacturing interests about 1850. In 1850 the population was 1,667; in 188o, in 1900, 33,988. Between 1910 and 1920 it increased 50.6%. Annexations of territory have brought the area to 4.7sq.m.