The Philadelphia region is the center of production for what crop in the United States?
Agaricus mushrooms, the conventional white button variety, are grown in nearby Chester county. In 1992, the county produced 37 percent of the nation’s fresh market sales and 69 percent of mushrooms used in processing. Source: Kestenbaum, Herbert, Ed. The Inquirer Regional Almanac, 1995. Philadelphia: Philadelphia Newspapers, Inc, 1994. p. 302.