It's a reversal for DowDuPont's predecessor companies, which sold and closed more factories than they opened in the Philadelphia area in the last 20 years. DuPont consolidated its headquarters to a suburban Wilmington site, closed its former Marshall (South Philadelphia) and Edge Moor (Delaware) plants, and reduced operations at the Experimental Station outside Wilmington and the Chambers Works complex in Salem County as part of the streamlining and spin-offs of some older business lines.