NAICS 321991

Overview

The North American Industry Classification System (NAICS) is the federal standard for classifying business establishments to produce comparable economic statistics. Developed jointly by the United States, Canada, and Mexico, it replaced the Standard Industrial Classification in 1997 under the Office of Management and Budget (OMB) and was most recently updated in 2022. ¹
U.S. Industry NAICS 321991 covers establishments primarily engaged in making manufactured homes (mobile homes) and nonresidential mobile buildings. These units are designed to accept permanent water, sewer, and utility connections and, although equipped with wheels, are not intended for regular highway travel. ²

What this NAICS covers

• Manufacture of manufactured homes (mobile homes). ²
• Production of nonresidential mobile buildings (e.g., mobile offices/classrooms). ²
• Factory construction of units engineered for permanent water, sewer, and utility hookups. ²
• Mobile dwellings equipped with wheels but not intended for routine highway movement. ²
• Assembly of wood-based components into completed manufactured home units — Not specified by official sources. ²

Related NAICS and PSC codes

Scope notes and cross-references

• Prefabricated wood buildings not equipped with wheels are classified in NAICS 321992, not NAICS 321991. ²
• Travel trailers and campers (towable recreational units) are classified in NAICS 336214, not NAICS 321991. ²

Data availability and implementation notes

• The Census Bureau began publishing data on the 2022 NAICS basis with the 2022 Economic Census “First Look” and plans full adoption across economic programs by the end of 2027. ⁴
• Manufacturing sector tables (NAICS 31–33), including data that can be filtered to NAICS 321991, are available through the 2022 Economic Census Manufacturing release. ⁵

Frequently asked questions

• What does NAICS 321991 include?
  It includes establishments that make manufactured homes (mobile homes) and nonresidential mobile buildings designed for permanent utility connections; these units may have wheels but are not intended for regular highway movement. ²

• How is NAICS 321991 different from NAICS 321992 and NAICS 336214?
  NAICS 321991 covers manufactured homes and mobile buildings. NAICS 321992 covers prefabricated wood buildings without wheels. NAICS 336214 covers travel trailers and campers. ²

• Are travel trailers, RVs, or motorhomes part of NAICS 321991?
  No. Travel trailers and campers are classified in NAICS 336214. Motorhomes (self-propelled) fall under motor vehicle manufacturing industries, not NAICS 321991. ²

• What is the SBA small business size standard for NAICS 321991?
  SBA’s current small business size standard for NAICS 321991 is 1,250 employees (effective March 17, 2023), per SBA’s Table of Small Business Size Standards. ⁶

• When will official statistics reflect the 2022 NAICS for this industry?
  Census began releasing 2022 NAICS-based results with the 2022 Economic Census and expects full program adoption by the end of 2027, with methods explained in program documentation. ⁴

Useful resources

• G2X — NAICS 321991 overview
• Census NAICS 321991 industry definition and cross-references. ²
• 2022 NAICS implementation timeline and program adoption status. ⁴
• 2022 Economic Census — Manufacturing (NAICS 31–33) data tables. ⁵
• GSA Product and Service Code Manual (PSC Group 54). ³

References

1. U.S. Census Bureau — Frequently Asked Questions about Industry and Occupation (NAICS history and 2022 reference). https://www.census.gov/topics/employment/industry-occupation/about/faq.html
2. U.S. Census Bureau — NAICS 321991 (2022) definition and cross-references. https://www.census.gov/naics/?input=321991&year=2022&details=321991
3. U.S. General Services Administration — Product and Service Code (PSC) Manual, April 2025 (Group 54). https://www.acquisition.gov/psc-manual
4. U.S. Census Bureau — Implementation of the 2022 NAICS (timeline and program adoption). https://www.census.gov/library/reference/code-lists/naics/2022/implementation-timeline.html
5. U.S. Census Bureau — 2022 NAICS Sector 31–33 Manufacturing (Economic Census tables). https://www.census.gov/data/tables/2022/econ/economic-census/naics-sector-31-33.html
6. U.S. Small Business Administration — Table of Small Business Size Standards (effective March 17, 2023). https://www.sba.gov/sites/default/files/2023-06/Table%20of%20Size%20Standards_Effective%20March%2017%2C%202023%20%282%29.pdf