Day & Zimmermann

aid: day-zimmermann
name: Day & Zimmermann
url: https://raw.githubusercontent.com/api-evangelist/day-zimmermann/refs/heads/main/apis.yml
type: Index
deliveryModel:
  model: unknown
  open_source: false
  commercial: false
  callable_host: false
  label: Delivery model not determined — needs a product licence on record
  confidence: low
  source:
  - none
  generated: '2026-08-28'
  method: derived
accessModel:
  pricing: unknown
  onboarding: unknown
  trial: false
  try_now: false
  public: false
  label: Unknown
  confidence: low
  source: []
  generated: '2026-07-22'
  method: derived
position: Producing
access: 1st-Party
image: https://kinlane-images.s3.amazonaws.com/shared/apis-json/icons/day-zimmermann.png
tags:
- Ammunition
- Architecture and Engineering
- Construction
- Defense
- Engineering Services
- Government Services
- Industrial Services
- Maintenance
- Munitions
- Nuclear Services
- Power
- Staffing
- Workforce Solutions
created: '2026-05-22'
modified: '2026-05-23'
specificationVersion: '0.23'
kind: company
description: Day & Zimmermann is a privately held, family-owned diversified industrial services company founded in 1901 and
  headquartered in Philadelphia, Pennsylvania. The company operates across four primary business segments — Maintenance &
  Construction (power, nuclear, fossil, renewable, and chemical plants), Munitions (ammunition manufacturing, storage, and
  demilitarization for the U.S. military, including operation of the Lake City Army Ammunition Plant), Government Services
  (security, EOD, facility management, and architecture/engineering for federal agencies), and Workforce Solutions (staffing
  and talent placement via Yoh). The Yoh family has controlled the company since 1961; Harold L. Yoh III serves as Chairman
  and CEO. Day & Zimmermann reported approximately $2.7 billion in revenue in 2023 with roughly 43,000–52,000 employees across
  approximately 150 global locations. Day & Zimmermann does not publish any public developer APIs; its business is delivered
  through long-cycle service contracts, government-owned contractor-operated (GOCO) facilities, and direct client engagements.
apis: []
common:
- type: DomainSecurity
  url: security/day-zimmermann-domain-security.yml
- type: Website
  url: https://www.dayzim.com
- type: About
  url: https://www.dayzim.com/who-we-are/
- type: Leadership
  url: https://www.dayzim.com/who-we-are/leadership/
- type: History
  url: https://www.dayzim.com/who-we-are/history/
- type: Maintenance and Construction
  url: https://www.dayzim.com/maintenance-and-construction/
- type: Munitions
  url: https://www.dayzim.com/munitions/
- type: Government Services
  url: https://www.dayzim.com/government-services/
- type: Workforce Solutions
  url: https://www.yoh.com
- type: Careers
  url: https://www.dayzim.com/careers/
- type: News
  url: https://www.dayzim.com/news-and-events/
- type: Contact
  url: https://www.dayzim.com/contact-us/
- type: LinkedIn
  url: https://www.linkedin.com/company/day-&-zimmermann
- type: Wikipedia
  url: https://en.wikipedia.org/wiki/Day_%26_Zimmermann
- url: https://www.dayzim.com/news
  type: Blog
segments:
- name: Maintenance and Construction
  description: Maintenance, construction, modification, and outage services for nuclear, fossil, and renewable power generation,
    plus chemical and industrial plants. Capabilities include welding, scaffolding, insulation, radiological protection, and
    turnkey plant services.
- name: Munitions
  description: Ammunition manufacturing, loading, assembly, packing, storage, and demilitarization for the U.S. Department
    of Defense. Day & Zimmermann operates the Lake City Army Ammunition Plant in Independence, Missouri under a government-owned
    contractor-operated (GOCO) arrangement, producing small caliber ammunition (5.56mm, 7.62mm, .50 caliber) for the U.S.
    Army. Additional product lines include medium caliber rounds, warheads, fuzes, and direct/indirect fire munitions.
- name: Government Services
  description: Integrated security services, explosive ordnance disposal (EOD), facility management, architecture, engineering,
    and commissioning for U.S. government agencies and federal installations.
- name: Workforce Solutions (Yoh)
  description: STEM staffing and talent placement operated through Yoh, a Day & Zimmermann company. Service lines include
    IT, engineering, life sciences, and healthcare staffing, along with RPO (Recruitment Process Outsourcing), MSP (Managed
    Service Provider), and EOR (Employer of Record) workforce models. Yoh maintains 6,000+ active contractors.
subsidiaries:
- name: Yoh
  description: STEM staffing and workforce solutions subsidiary.
  url: https://www.yoh.com
- name: Day & Zimmermann NPS
  description: Nuclear power services division.
- name: SOC LLC
  description: Government security services subsidiary.
customers:
- name: U.S. Army
- name: U.S. Department of Defense
- name: U.S. Department of Energy
- name: U.S. Nuclear Regulatory Commission-licensed utilities
- name: Investor-owned utilities
- name: Chemical and petrochemical operators
- name: Federal civilian agencies
facilities:
- name: Lake City Army Ammunition Plant
  location: Independence, Missouri
  role: Operator (GOCO)
  output: Small caliber ammunition for the U.S. Army
- name: Corporate Headquarters
  location: Philadelphia, Pennsylvania
ownership:
  type: Privately held
  family: Yoh family (since 1961)
  chairman: Harold L. Yoh III
  founded: 1901
  founders:
  - Charles Day
  - Kern Dodge
  - John Zimmermann (joined 1907)
scale:
  revenue: ~$2.7B (2023)
  employees: ~43,000–52,000
  locations: ~150 global
  ranking: Ranked among Engineering News-Record Top 500 Design Firms
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com