Industry Classifications Used in Authority Industries Directory

The Authority Industries Directory organizes service providers across the United States using a structured classification system that assigns each listed entity to a defined industry category. This page explains how those classifications are constructed, how they determine where a provider appears within the directory, and what boundaries separate one category from another. Understanding the classification framework helps users locate relevant providers efficiently and helps businesses determine where their services fit within the directory's national service categories.

Definition and scope

An industry classification, in the context of a service provider directory, is a formal assignment that places a business or professional entity within a recognized sector based on its primary operational activity. The Authority Industries Directory draws on two established public classification frameworks: the North American Industry Classification System (NAICS), maintained by the U.S. Census Bureau (U.S. Census Bureau, NAICS), and the Standard Industrial Classification (SIC) system, maintained historically by the U.S. Department of Labor and now referenced by the Securities and Exchange Commission (SEC SIC Manual).

NAICS uses a 6-digit hierarchical code structure. The first 2 digits identify a sector (e.g., 23 for Construction), digits 3–4 identify a subsector, digit 5 identifies an industry group, and digit 6 identifies a specific national industry. SIC codes use a 4-digit structure with a similar hierarchical logic but were last comprehensively updated in 1987, making NAICS the preferred reference for active directory classification.

The scope of the Authority Industries Directory spans service-oriented industries across all 50 U.S. states. Classification within the directory does not confer legal status, licensing recognition, or regulatory standing — it is an organizational tool that determines discoverability and category placement within the directory's listings.

How it works

When a provider is entered into the Authority Industries Directory, its primary service activity is mapped to the most specific applicable NAICS code. That mapping determines placement within one of the directory's top-level vertical categories. A provider with NAICS code 621111 (Offices of Physicians, except Mental Health Specialists) would be classified under Health & Medical Services, not under General Professional Services, even if the practice also provides administrative consulting.

The classification process follows this structured sequence:

1. Primary activity identification — The service or product that generates the majority of a provider's revenue or activity is identified as the primary business function.
2. NAICS code lookup — The primary activity is matched against the NAICS code search tool published by the U.S. Census Bureau, selecting the 6-digit code with the narrowest applicable definition.
3. Directory vertical assignment — The NAICS sector (first 2 digits) is mapped to a corresponding directory vertical (e.g., sector 54, Professional, Scientific, and Technical Services, maps to the directory's Professional Services vertical).
4. Secondary classification tagging — Where a provider operates across two distinct service areas, a secondary classification tag is applied. This tag affects search filtering but does not change the primary vertical assignment.
5. Review against listing criteria — The classification is validated against eligibility rules before the listing is published.

Providers that cannot be matched to a 6-digit NAICS code with reasonable specificity are held for manual review rather than assigned a catch-all code, which preserves the integrity of category structure across the directory.

Common scenarios

Single-activity businesses present the most straightforward classification. A licensed electrical contractor operating under NAICS 238210 (Electrical Contractors and Other Wiring Installation Contractors) maps directly to the Construction & Trades vertical without ambiguity.

Multi-service firms present classification decisions that require primary-activity analysis. A firm offering both IT consulting (NAICS 541512) and cybersecurity services (NAICS 541519) would be classified under whichever activity constitutes the dominant share of engagements. If that split cannot be verified, NAICS 541512 is applied as the broader parent classification.

Franchise and national chain locations are classified at the service-delivery level, not the corporate level. A national pest control franchise location operating under NAICS 561710 (Exterminating and Pest Control Services) is classified in the Facility & Property Services vertical, regardless of the corporate parent's broader business portfolio.

Licensed professional practices — including law firms, CPA offices, and engineering consultancies — follow the service provider types framework, which distinguishes between individual practitioner listings and firm listings. Both are classified using NAICS but display differently within their vertical.

Decision boundaries

The most consequential classification boundary is between NAICS Sector 54 (Professional, Scientific, and Technical Services) and NAICS Sector 56 (Administrative and Support and Waste Management and Remediation Services). A business providing specialized technical analysis belongs in Sector 54; a business providing general administrative staffing or facilities support belongs in Sector 56. Misclassification between these two sectors is the most frequent correction identified during directory maintenance reviews, as described in the update and maintenance policy.

A second critical boundary separates retail product sellers from service providers. The Authority Industries Directory is scoped to service delivery. A business whose NAICS code falls within Sector 44–45 (Retail Trade) is outside directory scope unless a secondary NAICS code confirms a distinct service component (e.g., a hardware retailer with a licensed installation division coded under 238990).

Contractors licensed in one state but offering services nationally are classified by service type, not by licensing jurisdiction. State-specific license status is a separate data field and does not alter classification. The compliance requirements section addresses how licensing data is stored and displayed independently of industry classification.

Where two equally valid NAICS codes apply and no primary-activity determination can be made, the code with the lower numeric value is selected as a tiebreaker to ensure deterministic, reproducible classification outcomes across the directory dataset.

References

• U.S. Census Bureau — North American Industry Classification System (NAICS)
• U.S. Securities and Exchange Commission — Standard Industrial Classification (SIC) Code List
• U.S. Bureau of Labor Statistics — NAICS Overview and Concordances
• U.S. Census Bureau — NAICS Frequently Asked Questions