As for how this could be, I offer one word: acquisitions.
They are why Comcast Corp.'s workforce grew 23.5 percent in one year. After acquiring NBC Universal in January 2011, the Philadelphia cable-television and Internet services company saw its roster of employees increase to 126,000 from 102,000.
The same was true for DuPont Co., the Wilmington chemical giant that had been keeping its workforce around the 60,000 mark for years. In 2011, it acquired food-ingredients maker Danisco A/S - DuPont's biggest acquisition in years - and added about 10,000 employees in the process.
Then there's Chadds Ford-based Endo Pharmaceutical Holdings Inc., which saw its labor force grow 55 percent, to 4,566 people. Back in 2008, when Endo was simply a maker of pain drugs, the company had just 1,216 employees. Since then, it has acquired a number of businesses, diversifying into other parts of the health-care industry.
Collectively, those 25 big regional companies - ranging from AmerisourceBergen Corp., the Valley Forge drug wholesaler with $80.2 billion in 2011 revenue, to SEI Investments Co., the Oaks financial-services firm with $930 million in 2011 revenue - employed 547,176 people, up from 506,951 in 2010.
Welcome news, even if it's tempered by the realization that nearly all that employment growth isn't occurring in the Philadelphia area.
An electronics company such as Vishay Intertechnology Inc. in Malvern has 89 percent of its 22,600 workers in factories outside the United States.
Hospital operator Universal Health Services Inc. may be based in King of Prussia, but few of its 25 acute-care hospitals, 198 behavioral-health centers, and 65,400 employees are local.
As for Philadelphia-based Crown Holdings Inc., whose workforce rose to 95,000 in 2011 from 89,000 the previous year, it operates 134 factories in 41 countries, and nearly all its expansions have been outside the United States.
Oddly, one company among those 25 that I expected to have a smaller workforce was Sunoco Inc., the Philadelphia oil refiner and marketer that has been doing it can to shed its refining operations.
According to its latest annual report, Sunoco had 10,500 employees in 2011, up from 10,200 in 2010. That 3 percent increase was driven by additions to the company's 4,933 retail gasoline outlets.
Also, Sunoco's 2011 employment numbers include 1,400 people who worked for SunCoke Energy, which was spun off in January 2012.
Contact Mike Armstrong at 215-854-2980 or email@example.com, or follow on Twitter @PhillyInc. Read his blog, "PhillyInc," at www.phillyinc.biz.