NAICS 221121

Overview

Federal statistical programs use the North American Industry Classification System to organize establishments by their primary production processes for consistent economic data. NAICS was created under the Office of Management and Budget with Statistics Canada and Mexico’s national statistics agency and was officially adopted in 1997; the current classification vintage used across Census economic programs is 2022. ⁶

NAICS 221121 covers establishments primarily engaged in operating bulk electric transmission systems and/or controlling the transmission of electricity from generating sources to distribution centers or other electric utilities; the transmission system includes high-voltage lines and transformer stations. It excludes generation activities classified under 22111 and distribution to end users classified under 221122. ²

What this NAICS covers

• Operation of high-voltage bulk power transmission lines and network assets. ²
• System control, dispatch, and voltage regulation for bulk power flows. ²
• Management and operation of transmission substations and transformer stations. ²
• Coordination of power transfers between generating sources and distribution centers or other utilities. ²
• Transmission reliability operations associated with moving electricity over bulk networks. ²
• Activities incidental to transmission control, excluding retail distribution and electricity generation. ²

Related NAICS and PSC codes

Scope notes and exclusions

• Included: Operating bulk transmission systems and controlling transmission (e.g., voltage regulation, dispatch). ²
• Excluded: Generating electric energy (see 22111). ²
• Excluded: Distributing electricity to final consumers (see 221122). ²
• Census publications using the 2022 NAICS vintage report Utilities sector statistics (Sector 22) on a 2022 basis, covering 221121 alongside related industries. ³
• Census program groupings list 221121 under “Electric Power Transmission, Control, and Distribution.” ⁴

Frequently asked questions

• What activities are included in NAICS 221121?

  • Covered activities include operating high-voltage bulk transmission systems and controlling transmission flow and voltage from generation points to distribution centers or other utilities. This includes the operation of substations and transformer stations integral to the transmission network, as well as related dispatch and reliability functions. ²

• How does 221121 differ from 221122?

  • 221121 covers bulk, high-voltage transmission and system control between generation and distribution networks. 221122 covers distribution to final consumers and related broker/agent activities using local distribution systems; these functions are explicitly out of scope for 221121. ²

• Is 221121 reported on a 2022 NAICS basis in recent Census releases?

  • Yes. 2022 Economic Census Utilities data are disseminated on the 2022 NAICS basis, with Sector 22 tables that include 221121. Users should reference the 2022 Utilities tables for current statistics and crosswalks to related industries within the sector. ³

• Do official sources specify whether independent system operator (ISO/RTO) control centers are classified here?

  • Not specified by official sources ²

• Which PSCs commonly align with bulk transmission operations or electricity supply buys?

  • For facility operations involving transmission-related EPG operations, agencies may use M1MZ. For commodity electricity supply from third-party generation, agencies may use 9105. PSC selection depends on acquisition specifics and agency guidance, separate from NAICS selection. ⁵

Useful resources

• G2X — NAICS 221121 overview
• U.S. Census Bureau — 2017 NAICS Manual (official NAICS definition and background). ¹
• U.S. Census Bureau — 2022 NAICS Sector 22: Utilities (Economic Census tables on a 2022 basis). ³
• U.S. Census Bureau — Implementation of the 2022 NAICS (timeline and program adoption). ⁶
• Acquisition.gov — Product and Service Code Manual (definitions for PSC M1MZ and 9105). ⁵

References

1. U.S. Census Bureau, 2017 North American Industry Classification System (NAICS) Manual. https://www.census.gov/library/publications/2017/econ/2017-naics-manual.html
2. U.S. Census Bureau, NAICS Sector 22—Utilities (archived definitions including 221121). https://www.census.gov/naics/resources/archives/sect22.html
3. U.S. Census Bureau, 2022 NAICS Sector 22—Utilities (Economic Census data on 2022 basis). https://www.census.gov/data/tables/2022/econ/economic-census/naics-sector-22.html
4. U.S. Census Bureau, Employer Categories and Corresponding Establishment NAICS Industries. https://www.census.gov/programs-surveys/esp/guidance/employer.html
5. Acquisition.gov, Product and Service Codes (PSC) Manual, April 2025. https://origin-www.acquisition.gov/sites/default/files/manual/PSC%20Manual%20April%202025.pdf
6. U.S. Census Bureau, Implementation of the 2022 NAICS (overview and timeline). https://www.census.gov/library/reference/code-lists/naics/2022/implementation-timeline.html