Pine Bluff, city (1990 pop. 57,140), seat of Jefferson co., S central Ark., on the Arkansas River; inc. 1839. It is a port and trade center for an agricultural area and has industries producing metal, wood, and paper products; machinery; electrical equipment; and foods. It is also a research center and the seat of the Univ. of Arkansas at Pine Bluff. Of economic importance to the city is the huge Pine Bluff Arsenal to the north; established during World War II, it is the center of U.S. army chemical, biological, and toxicological research. Pine Bluff has an arts and science center and a civic complex designed by Edward Durell Stone.