Name: Day & Zimmermann Inc.

Where: Philadelphia.

Business: Contract engineering and technical company specializing in defense, munitions, energy, security, logistics, construction management.

Subsidiary: Yoh Services L.L.C., a staffing company.

Revenue: $2.5 billion

Employees: 23,000 in 150 locations globally, 400 here.

History: Family business, founded in 1901, now run by third generation.

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