Fiber, Yarn, and Thread Mills (U.S.) — NAICS 3131

An investor's primer for the NAICS industry group (4-digit) level. Figures are U.S. federal statistics unless noted; forward-looking statements are labeled as judgments in the text.

Short page by design. NAICS 3131 is a single-child rollup: this 4-digit industry group contains exactly one industry, 31311 (Fiber, Yarn, and Thread Mills), which in turn contains one national industry, 313110. All three codes cover the same mills, the same firms, and the same output. This page states what the level is, gives its own ground-truth federal stats, and points you to the full 31311 primer for the deep detail. Nothing here contradicts that page — it is the same industry viewed one rung up the taxonomy.

1. Overview

NAICS 3131 is the U.S. industry group that turns raw fiber — cotton, wool, or synthetic staple and filament — into yarn (the continuous strand woven or knit into fabric) and thread (the finished strand used to sew products together). It is the first conversion step of the textile supply chain: a T-shirt, an airbag, or a car seat all begin with yarn spun by a mill in this code.

It is a small, capital-intensive, and shrinking corner of U.S. manufacturing — roughly $6.6 billion in receipts and about 18,300–20,100 workers depending on source and year [1][2][3] — and one of the most trade-exposed industries in the country. For an investor, the practical takeaway is that there is essentially one pure-play listed U.S. company (Unifi, Inc.) and a set of large private or foreign-owned operators (Parkdale, American & Efird, National Spinning, Buhler) that actually dominate the level. It is a specialist's or private-ownership play, not an index sector [7][8].

2. What's inside — and why this level equals its one child

The NAICS 2022 hierarchy places one industry, and one national industry beneath it, under 3131:

Because the Census Bureau defined only a single industry beneath this 4-digit group — and only a single national industry beneath that — 3131, 31311, and 313110 cover exactly the same establishments, the same firms, and the same output. There is no aggregation happening here: no second child to add in, no mix to weigh. That is why this page is short. For scope (what's in and what's out — spinning and thread-making in; synthetic-fiber production in NAICS 325220 out; weaving and knitting in NAICS 3132 out), economics, and company detail, read the 31311 primer directly [9].

3. Size (this level's rollup figures)

The figures below are our ingested federal ground truth for 3131 specifically. Because the group has one child, they equal the 31311 and 313110 numbers. Two of them — the Federal Reserve's value-added estimate and the BLS productivity series — are in fact published natively at this 4-digit level, which is the one respect in which 3131 has statistics of its own rather than borrowed ones [3][4].

How to read this. Output is top-heavy but not monopolistic: the top four firms make more than half the total, yet the HHI of 952.5 sits just below the U.S. Department of Justice's 1,000 "unconcentrated" threshold, because roughly 200 smaller mills sit under the leaders [2]. The whole group qualifies as "small business" by federal definition — with employment spread across 250 plants (about 73 per plant), only the very largest operators approach the 1,250-employee line [1][6].

Where the sources disagree. Headcount is the one figure that does not settle: County Business Patterns puts 2023 employment at 18,290, while the BLS productivity series for NAICS 3131 carries roughly 20,100 for 2025 [1][3]. The gap is definitional and vintage-driven, not a correction of one by the other — treat "roughly 18,000–20,000" as the honest range rather than picking a point estimate.

Undercount caveat (read this — it cuts a specific way). Unlike restaurants or trades, this industry group is not undercounted by tiny or informal operators — these are real, incorporated, capital-intensive plants that the Census captures well. The distortion runs the other way: the federal figure counts U.S. soil only, so it understates the global footprint of U.S.-headquartered yarn companies (Parkdale runs about 29 plants across the U.S. and Latin America; Unifi and American & Efird operate across Brazil, Central America, and Asia) [7][10][11]. Separately, some vertically integrated mills that spin yarn only to feed their own looms get classified by their fabric output, so a slice of domestic spinning capacity sits outside this code. No value in the table is suppressed.

4. Investable universe (where value concentrates)

Because the group equals its one child, value concentrates exactly where it does in 31311/313110: in a handful of large operators, almost all of them private.

Bottom line: the level is effectively un-investable through equities beyond a single micro-cap; there is no U.S. yarn-mill ETF (exchange-traded fund). Broader exposure is built downstream (branded apparel, technical textiles) or upstream (man-made-fiber and chemical producers in NAICS 325220). Full detail on the private and roll-up routes is in the 31311 primer [7][8].

5. How the money works

Yarn spinning is a conversion (spread) business: a mill buys fiber, sells yarn, and earns the gap between the two minus conversion cost. Both ends are commodity-priced, so mills have little pricing power and depend on the spread and on volume — the BLS producer-price index for cotton spun yarn stood at 82.2 in June 2026 against a May 2022 base of 100, meaning selling prices roughly 18% below that base period [14]. Capacity utilization is everything: the plant is capital-heavy, so running it full spreads fixed cost, and idle spindles bleed cash. How punishing that is shows up in the one public set of books — Unifi's Americas segment posted gross loss margins of 3.8% (FY2023), 5.1% (FY2024), and 5.8% (FY2025), attributed largely to poor manufacturing utilization, and cost increases pass through only with a lag of up to two fiscal quarters [7].

Input costs are fiber (cotton, purchased polyester) and, increasingly, electricity, which was blamed directly for several 2024–26 U.S. plant closures [15][16][17]. Government money is part of the model too: the U.S. Department of Agriculture's Economic Adjustment Assistance for Textile Mills (EAATM) cotton payment (raised from 3¢ to 5¢ per pound effective August 2025), plus tariff and "yarn-forward" trade protection [18]. See the 31311 primer §5 for the full economics.

6. Demand drivers

Yarn demand is derived from downstream fabric, apparel, home-textile, and industrial-goods production. The structural demand engine is the "yarn-forward" rule of origin in the CAFTA-DR (Dominican Republic–Central America Free Trade Agreement) and USMCA (United States–Mexico–Canada Agreement) trade deals, which grant apparel duty-free U.S. access only if the yarn (and everything forward) is made within the region — effectively making U.S. spinners the mandatory supplier for a nearshore apparel bloc; U.S. yarn exports were about $4.0 billion in 2024 [19][20][21]. Since 2021 USMCA has extended the same logic to sewing thread, which must itself be originating for apparel to qualify [20].

The long-term volume story underneath that policy floor is poor. USDA put domestic cotton mill use at 1.9 million 480-pound bales in 2023/24, the lowest in nearly 140 years, and by 2026 exports accounted for more than 85% of demand for U.S. raw cotton versus under 40% in the 1990s — because the spinning itself has moved offshore [22][23]. Reshoring away from China, growth in technical/industrial yarns (airbags, seatbelts, medical, filtration), and brand commitments to recycled content are the growth pockets [24][25].

7. Regulation

Regulation here is overwhelmingly trade policy, and it is unusually favorable to domestic spinners: yarn-forward rules of origin, Section 301 China tariffs, the closing de minimis loophole (the low-value duty-free import allowance ended for China in May 2025, with full repeal codified for July 2027), the Berry and Kissell Amendments requiring U.S.-made textiles for defense and some homeland-security purchases, and the USDA EAATM cotton payment [18][20][24].

Two non-trade rules are distinctive enough to name rather than wave at: OSHA's cotton-dust standard (29 CFR 1910.1043) applies in full to yarn manufacturing, a compliance burden specific to this level rather than generic workplace safety, and mills running wet cleaning, dyeing, or finishing steps fall under EPA's Textile Mills Effluent Guidelines [26][27]. The flip side of the trade regime is that the industry is a policy beneficiary, so its fortunes are unusually sensitive to trade-agreement renegotiation — USMCA's scheduled joint review is a live event [28]. Other standard manufacturing regulation (environmental permitting, energy policy) applies but is not distinctive.

8. Consolidation

The dominant dynamic is a decades-long, ongoing shakeout: U.S. textile-and-apparel employment has fallen to roughly 471,000 supply-chain-wide, and the number of mills has roughly halved since 1997 [19][29]. It continues in real time, and the closures are concentrated at the commodity end rather than among marginal players — even market leader Parkdale Mills shut four U.S. plants across 2024–2026 (Sanford and Walnut Cove, North Carolina; Mountain City, Tennessee; and a 109-year-old Hillsville, Virginia facility), several blamed explicitly on rising energy costs [10][15][16][17]. Unifi simultaneously restructured its U.S. footprint toward higher-value recycled and performance yarns [7]. Scale commodity players win on cost; differentiators (recycled, fine-count, specialty thread) defend margin. Fresh capital comes mainly from private-equity roll-ups (Elevate Textiles) and foreign strategic owners (Buhler), not new entrants.

9. Risks

• Structural import competition — cheap Asian yarn and finished apparel is the permanent headwind; survival is tied to protective policy [24][29].
• Energy-cost exposure — spinning's electricity intensity was the proximate cause of several 2024–26 closures [15][16][17].
• Trade-policy reversal — demand leans on yarn-forward rules, Berry/Kissell content rules, and Section 301 tariffs; any weakening hits demand directly [20][28]. This is the central forward-looking risk.
• Commodity margin squeeze — cotton and polyester price swings compress the thin spinning spread, and repricing lags of up to two quarters squeeze margins even where costs are eventually passed through [7][30].
• Input sourcing concentration — dependence on qualified regional suppliers for CAFTA-DR, USMCA, and Berry Amendment-compliant products narrows sourcing flexibility [7].
• Cyclicality and thin balance sheets — the one public play trades near cash and has posted losses, showing how little margin for error the level carries [7][8].

10. How to invest & outlook

Public routes are limited. Unifi (NYSE: UFI) is the only listed pure-play — a micro-cap deep-value/turnaround levered to recycled yarn (REPREVE) and trade policy, with recent negative Americas gross margins making it a restructuring and utilization-recovery bet rather than clean industry beta. Broader, more liquid exposure comes from adjacent upstream man-made-fiber/chemical producers (NAICS 325220) or downstream branded-apparel and technical-textile names. There is no U.S. yarn-mill fund or ETF [7][8].

Private routes are where the industry actually is: direct ownership or acquisition of family-owned mills facing succession pressure; supplier, off-take, and real-estate angles tied to nearshore apparel co-production; and PE (private-equity) roll-ups of differentiated (technical, sustainable, specialty-thread) capacity.

The honest outlook (judgment): a mature, policy-dependent, consolidating industry, not a growth sector — continued shrinkage of commodity spinning offset by pockets of growth in recycled, performance, and industrial yarns, with the floor set largely by how protective U.S. trade policy stays. Treat it as a specialist, contrarian, or private-ownership play. For the complete analysis, read the 31311 primer.

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Sources

1. U.S. Census Bureau, County Business Patterns 2023 — NAICS 313110 (establishments, employment, annual and first-quarter payroll). https://www.census.gov/programs-surveys/cbp.html
2. U.S. Census Bureau, 2022 Economic Census — Concentration Ratios and Receipts, NAICS 313110 (receipts, firm count, CR4/CR8/CR20/CR50, HHI). https://www.census.gov/programs-surveys/economic-census.html
3. U.S. Bureau of Labor Statistics, 2025 Productivity and Costs by Industry — NAICS 3131 (employment, output, hours, labor productivity, unit labor costs). https://www.bls.gov/news.release/prin.htm
4. Federal Reserve, Industrial Production Source and Description Tables (NAICS 3131 value added, 2022). https://www.federalreserve.gov/RELEASES/G17/SandDesc/sdtab1.pdf
5. U.S. Bureau of Labor Statistics, Occupational Employment and Wage Statistics, May 2023 — NAICS 313100 (mean annual wage). https://www.bls.gov/oes/2023/may/naics4_313100.htm
6. U.S. Small Business Administration, Table of Small Business Size Standards — NAICS 313110 (1,250 employees), 2023. https://www.sba.gov/document/support-table-size-standards
7. UNIFI, Inc., Form 10-K, Fiscal Year 2025 (consolidated and segment financials, REPREVE sales, customer concentration, gross margins, input risks). https://www.sec.gov/Archives/edgar/data/100726/000095017025111331/ufi-20250629.htm
8. StockAnalysis, Unifi (UFI) — Revenue and Market Cap, 2026. https://stockanalysis.com/stocks/ufi/
9. IBISWorld, NAICS 313110 — Fiber, Yarn, and Thread Mills (industry definition and exclusions), 2025. https://www.ibisworld.com/classifications/naics/313110/fiber-yarn-and-thread-mills/
10. Parkdale Mills, Company Overview / Yarn Manufacturing, 2025. https://www.parkdalemills.com/
11. American & Efird / Elevate Textiles, Company Overview and Brand Portfolio, 2025. https://www.amefird.com/about-us/overview-2/; https://www.elevatetextiles.com/
12. National Spinning Company, Company Overview, 2025. https://www.natspin.com/
13. CB Insights, Buhler Quality Yarns (subsidiary of Hermann Bühler AG) — company profile, 2025. https://www.cbinsights.com/company/buhler-quality-yarns
14. U.S. Bureau of Labor Statistics, Producer Price Index — Cotton spun yarn (series via FRED). https://fred.stlouisfed.org/series/PCU31311031311042
15. Business North Carolina, Parkdale Mills closing Lee County plant and related 2024–2025 closure reports. https://businessnc.com/parkdale-mills-closing-lee-county-plan/
16. When In Your State, A 109-year-old textile company is closing its Hillsville facility as energy costs rise, 2025. https://wheninyourstate.com/virginia/a-109-year-old-textile-company-is-closing-its-hillsville-facility-as-energy-costs-rise/
17. Charlotte Observer, Parkdale Mills closing North Carolina plant, April 2026. https://www.charlotteobserver.com/news/business/article314408934.html
18. U.S. Department of Agriculture, Agricultural Marketing Service / Federal Register, Economic Adjustment Assistance for Textile Mills — Payment Rate (3¢ to 5¢ per pound, effective August 2025), 2026. https://www.federalregister.gov/documents/2026/02/24/2026-03645/economic-adjustment-assistance-for-textile-mills-payment-rate
19. National Council of Textile Organizations (NCTO), U.S. Textile Industry — Facts & Figures, 2024 (shipments, supply-chain employment, yarn exports). https://ncto.org/facts-figures/us-textile-industry/
20. U.S. Department of Commerce (trade.gov) and USTR, Summary of CAFTA / USMCA Textile Provisions (yarn-forward rules of origin; sewing-thread origin requirement effective 2021); Berry Amendment, 2019–2025. https://www.trade.gov/summary-cafta-fta-textiles; https://www.trade.gov/summary-usmca-fta-textiles
21. National Cotton Council, The Economic and Societal Impact of the Yarn-Forward Rule, 2022. https://www.cotton.org/issues/2022/upload/22nctostudy.pdf
22. U.S. Department of Agriculture, Economic Research Service, U.S. cotton mill use at historic low, 2024. https://www.ers.usda.gov/data-products/charts-of-note/108272
23. U.S. Department of Agriculture, Economic Research Service, Exports dominate demand for U.S. cotton, 2026. https://ers.usda.gov/data-products/chart-gallery/58352
24. National Council of Textile Organizations (NCTO), Statements on Section 301 tariffs and de minimis elimination, 2025. https://ncto.org/policy-positions/trade-policy/
25. Fortune Business Insights / MarketsandMarkets, Technical Textiles Market Size and Forecast, 2025. https://www.fortunebusinessinsights.com/technical-textiles-market-102716
26. U.S. Occupational Safety and Health Administration, Cotton Dust Standard, 29 CFR 1910.1043. https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1043
27. U.S. Environmental Protection Agency, Textile Mills Effluent Guidelines. https://www.epa.gov/eg/textile-mills-effluent-guidelines
28. National Council of Textile Organizations (NCTO), U.S. Textile Industry Urges Stronger USMCA Rules, 2025. https://ncto.org/
29. Congressional Research Service (via EveryCRSReport), Renegotiating NAFTA and U.S. Textile Manufacturing (R44998), employment and mill-count history. https://www.everycrsreport.com/reports/R44998.html
30. Kentley Insights, U.S. Yarn & Thread Mills Market Report 2025. https://www.kentleyinsights.com/yarn-thread-mills-market-report/