Administrative & Support Services

NAICS 561 covers firms that perform routine operational and administrative functions for other organizations — temporary staffing, facilities management, security, janitorial services, call centers, document preparation, and travel arrangement. The subsector is one of the largest private-sector employers in the US, with 13.0 million employees (Census CBP, 2023), many of them placed through staffing agencies into client worksites across every industry.

The staffing segment alone is massive. The American Staffing Association (ASA) reported that US staffing firms employed roughly 12.7 million temporary and contract workers over the course of 2023, generating estimated revenue above $200 billion. Robert Half, Randstad (through its US operations), Kelly Services, and Manpower Group are the largest publicly traded staffing firms, though the segment remains fragmented with thousands of regional and niche agencies. On the facilities side, ABM Industries, Cushman & Wakefield's services division, and Cintas dominate janitorial, landscaping, and uniform-services contracts.

Regulatory attention has sharpened around worker classification. The Department of Labor's 2024 independent-contractor rule under the FLSA replaced the Trump-era simplified test with a six-factor economic-reality analysis, directly affecting staffing firms and gig-platform operators that classify workers as 1099 contractors. California's AB 5 and its carve-out amendments remain the strictest state-level classification statute. In the security segment, state licensing boards govern armed and unarmed guard certification, while federal contracts require compliance with the Service Contract Act's prevailing-wage and benefits provisions.