NAICS 33111 — Iron and Steel Mills and Ferroalloy Manufacturing

A rollup primer. NAICS = North American Industry Classification System, the U.S. government's standard code for industries. This is a five-digit "NAICS industry" that contains exactly one six-digit "national industry," 331110. For a general investing audience — public-market and private investors alike.

1. Overview

NAICS 33111 covers the businesses that make steel from scratch: reducing iron ore, making pig iron, converting iron into steel, melting steel, casting and rolling it into sheet, plate, bar, rod, strip, wire, and pipe — plus the manufacture of ferroalloys, the manganese-, silicon-, chromium- and molybdenum-bearing additives that give steel its chemistry and performance [1]. The classification is process-based: a plant that only rolls, draws, or forms steel it bought from someone else generally sits in NAICS 3312, not here. This is heavy, capital-intensive commodity manufacturing — a small number of companies running a small number of very large plants. It is the top of the domestic steel supply chain and a classic cyclical tied to construction, autos, machinery, and energy.

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

A five-digit NAICS industry normally splits into several six-digit national industries. This one does not: 33111 contains a single child, 331110 (also named "Iron and Steel Mills and Ferroalloy Manufacturing"). Their scope is identical — the five-digit and six-digit codes describe the same set of companies, plants, and products. So everything that is true of 331110 is true of 33111. Our ground-truth stats file for the six-digit child was not separately ingested, so the five-digit federal figures below stand in for both; the revised child research adds a Census six-digit industry profile that agrees on plant count but reports meaningfully higher employment (see §3).

The one structural fact worth stating at this level is how few operators there are, and how lopsidedly they split by production route. At the start of 2025, two companies operated integrated blast-furnace steelmaking at eight active locations, while 47 companies ran electric-arc-furnace (EAF) "minimills" at 102 sites [2]. The U.S. Department of Energy reports that EAFs now make 70% of domestic steel, and that remelting scrap in an EAF takes less than half the energy of making steel from ore through a blast furnace [3]. The parent page previously described the country as merely "majority-EAF"; the revised research puts a number on it, and the number is decisive.

This page is a short pass-through. The full detail — route-by-route economics, company-level metal spreads and input ratios, trade and environmental rules, and the investable names — lives in the 331110 primer. Read that for the deep dive.

3. Size (this level's rollup figures)

Federal ground truth for 33111 (which, again, equals 331110). Note that the measures below come from four different programs and four different years — they are not alternative estimates of one number:

The sources disagree on employment. County Business Patterns reports 78,532 workers for 2023 [7]; the Census Bureau's own six-digit industry profile, as retrieved in the revised child research, reports average employment of about 86,000 [8]. That is roughly a 10% gap, and it is not reconciled — use whichever series you can hold constant across years rather than mixing them. On the County Business Patterns basis, payroll works out to roughly $116,000 per worker [7] — high pay reflecting skilled, heavily unionized, capital-intensive work. Physical output includes about 21 million tons of pig iron alongside the 82 million tons of raw steel in 2025, and 99.7% of U.S. steel is continuously cast [2].

Two counts of "how many companies" that should not be reconciled. The Census firm count (73, in 2022) covers firms whose establishments are classified in this industry; the USGS count (two integrated producers plus 47 EAF producers, at the start of 2025) covers companies actually operating raw-steel furnaces [2][4]. Likewise, the 359 establishments are all payrolled operating locations in the industry, a wider net than the eight integrated locations and 102 minimills that make raw steel. Do not subtract or divide across the two.

Undercount caveat (reversed here). The usual small-shop/nonemployer undercount that plagues fragmented industries does not apply — with 73 firms and 359 plants, federal data captures this industry almost completely. The previous version of this page asserted that public stock-market value understates the industry because so much of it is private or foreign-owned. That direction is plausible but is now explicitly unquantified: the revised child research states that a public-versus-private share of output could not be established from available sources, and neither could the share of revenue attributable specifically to ferroalloys. Treat both as open questions rather than settled facts.

4. Investable universe (where value concentrates)

Because 33111 is a single industry with no sub-industries, value does not split across "children" — it concentrates across a short list of dominant firms. On 2022 Economic Census data, the top 4 firms take 59.5% of revenue, the top 8 take 75.1%, and the top 20 take 94.4% [4]. Read those as a 2022 snapshot: the revised child research states that a current four-firm concentration ratio could not be established from available sources.

The listed exposure is genuinely narrow, and the names differ by route rather than by product alone. Nucor (NYSE: NUE) is the largest U.S. EAF producer, with steel mills at 62% of 2025 external sales and 25.271 million tons shipped through the segment [9]. Steel Dynamics (Nasdaq: STLD) is a diversified EAF producer, steel operations at 72% of 2025 consolidated sales on 13.749 million tons shipped [10]. Cleveland-Cliffs (NYSE: CLF) is the integrated ore-to-steel producer, 18.8 million net tons made in 2025 against 20.0 million tons of configured North American capacity, with a large automotive book and heavy union and legacy-liability exposure [11]. Commercial Metals (NYSE: CMC) adds long-products and rebar. Foreign listings carry the rest: Nippon Steel (Tokyo: 5401) since its acquisition of U.S. Steel [12][13], Gerdau (NYSE: GGB), and BlueScope Steel, parent of the North Star EAF flat-roll mill in Ohio.

One caution the child page is emphatic about, and that matters most at a rollup level: company tonnage figures include internal transfers, downstream processing, and sometimes Canadian output, so they cannot be divided into the USGS U.S.-only totals above to manufacture market shares. The full name-by-name treatment, including private and upstream exposures, is in 331110 (§4).

5. How the money works

At this level the economics are simply those of 331110: a commodity manufacturer whose margin is a spread — realized selling price minus the cost of metallic inputs — levered by how full the plant runs. Steel Dynamics reports that metallic inputs are normally 55%–65% of steel-mill manufacturing cost [10]. On the integrated side, Cleveland-Cliffs estimates a net ton of raw steel consumes roughly 1.4 net tons of iron-ore pellets or equivalent, 0.3–0.4 tons of coke, 0.3 tons of scrap, and 5–6 MMBtu of natural gas, against about 1.1 tons of metallic input per ton in its EAFs [11]. Integrated mills carry very high fixed costs and expensive shutdowns; EAFs start and stop more readily but sit closer to scrap and electricity prices [4 → see 331110 §2; 3][11].

Utilization is the second lever: Nucor's steel-mill utilization rose from 76% in 2024 to 83% in 2025, more tonnage over the same asset base [9].

There is no single "industry margin," and the 2025 spread between the two routes is the clearest evidence. In the same year, Cleveland-Cliffs reported a negative 5% steelmaking gross margin while Steel Dynamics' steel operations earned $1.428 billion of operating income on $13.413 billion of sales — about a 10.6% operating margin, even as its own metal spread narrowed 2% and segment operating income fell 10% [10][11]. Any figure quoted as "the" margin for this industry is really a statement about one route and one product mix. Working capital reinforces the cycle: mills and service centers build costly inventory into rising prices, and the subsequent destock cuts orders harder than end demand falls. Full mechanics are in 331110 (§5).

6. Demand drivers

The revised research replaces the old company-anecdote framing with a federal breakdown of 2025 U.S. net steel shipments by market: construction 31%, service centers and distributors 26%, automotive 15%, converting and processing 11%, and all other uses 17% [2]. The 26% sitting with distributors is worth dwelling on — a quarter of shipments go to intermediaries whose restocking and destocking can temporarily dominate real end-market demand.

Underneath that, demand is nonresidential and infrastructure construction, autos, machinery and appliances, energy pipe and tube, and — newer — data centers, grid and transmission investment, and reshored semiconductor and battery plants. In 2025 Nucor described strong demand from infrastructure, data centers, energy, and advanced manufacturing, with automotive and residential construction softer; Steel Dynamics pointed to infrastructure funding, onshoring, and regionalized supply chains [9][10]. Because these are capital-goods and building end-markets, the industry rises and falls with interest rates, construction starts, and vehicle production. Over a longer horizon the mix keeps moving toward EAFs, higher-quality scrap substitutes, and lower-carbon iron; the Department of Energy names hydrogen-based direct-reduced iron, iron electrolysis, electrified reheat furnaces, and carbon capture as priority technologies, several of which still need cost reduction and commercial-scale demonstration [14]. See 331110 (§6).

7. Regulation

Three forces dominate, all covered in 331110 (§7). First, trade policy: Section 232 of the Trade Expansion Act lets the President tax imports on national-security grounds, and as of April 2026 the U.S. applied a 50% rate to articles made entirely or almost entirely of steel and 25% to qualifying derivative articles [15]. The U.S. International Trade Commission's study of the earlier Section 232 measures found they cut affected imports 24%, raised U.S. steel-product prices 2.4%, and lifted domestic production 1.9% on average over 2018–2021 — while raising downstream prices and reducing downstream production [16]. Protection transfers economics to the mills, but at the expense of the customers that buy from them.

Second, environmental rules, which are route-specific. The U.S. Environmental Protection Agency's amended hazardous-air-pollutant standards (NESHAP) for integrated iron and steel mills require maximum-achievable-control technology on sinter plants, blast furnaces, and basic-oxygen shops [17]; EAFs escape most of the blast-furnace carbon burden but generate particulate emissions and hazardous furnace dust and are exposed to grid power prices. The spending is real but not ruinous at the top end of the industry: Nucor expects roughly $250 million of safety and environmental spending in 2026 and estimates environmental-compliance capital expenditure at existing facilities below $100 million a year in both 2026 and 2027 [9].

Third — and new to this page — labor is a regulatory-grade constraint, not just a cost line. More than 90% of Cleveland-Cliffs' hourly workforce is union-represented, with several major site agreements up for negotiation in 2026, and the company flags shortages of electricians and other experienced industrial workers [11]. Work stoppages, wage escalation, and retiree obligations bear hardest on integrated mills.

8. Consolidation

The industry is already concentrated — a Herfindahl-Hirschman Index (a standard concentration measure) of 1,071.9, just inside the "moderately concentrated" band, on 73 firms, per the 2022 Economic Census [4]. As with the concentration ratios in §4, no current HHI could be established in the revised research, so this is a 2022 reading rather than today's. Nippon Steel of Japan completed its acquisition of U.S. Steel on June 18, 2025 [12][13], taking a marquee American name off the U.S. public market. Nucor assembled its position through acquisitions, and integrated capacity clustered under Cleveland-Cliffs through its combinations with the legacy AK Steel and ArcelorMittal USA assets. Further consolidation may be limited by antitrust review, particularly for deals combining integrated capacity that serves automotive customers.

The larger competitive pressure is external. The OECD estimates global excess steelmaking capacity reached 640 million tonnes in 2025 and projects 745 million tonnes by 2028 [18]. Even where tariffs block direct imports, displaced foreign steel depresses world prices, reroutes through third countries, and provokes further trade actions. Domestically, competition is segmented by route and by customer qualification: EAF sheet keeps displacing integrated sheet, but automotive-qualified grades, electrical steel, and specialty products demand certifications and capital that are slow to replicate. Private and foreign ownership — BlueScope's North Star mill, numerous regional minimills and specialty and ferroalloy producers — sits alongside the listed names; how much of output that represents is not established (§3).

9. Risks

The same risks as 331110 (§9): metal-spread compression, when input prices rise before selling prices reset or selling prices fall before input costs do; deep cyclicality tied to construction and auto capital spending, amplified by distributor destocking; utilization volatility, where high fixed costs turn a demand dip into severe margin damage and capacity additions can overshoot; global overcapacity at 640 million tonnes and rising [18]; trade-policy reversal, since Section 232 rates are changeable by executive action, exemption, or litigation; environmental compliance and decarbonization capital expenditure [17]; labor constraints — union negotiations, skilled-worker shortages, and legacy pension and retiree obligations, concentrated at integrated mills [11]; customer concentration among large automakers, builders, and distributors; inventory losses on high-cost metal bought near a peak; technology-transition risk, if hydrogen DRI or carbon capture investments miss on cost or timing [14]; and substitution by aluminum, composites, engineered wood, and concrete.

10. How to invest & outlook

For public-market investors, the first decision is route, not ticker: EAF-focused exposure with downstream integration (Nucor, Steel Dynamics) versus integrated ore-to-steel exposure with automotive concentration and higher operating leverage (Cleveland-Cliffs). Nippon Steel offers the former U.S. Steel assets through a foreign listing [12][13]; a steel-industry exchange-traded fund gives a diversified basket. Valuation should be built on mid-cycle earnings rather than peak metal spreads, using enterprise value to EBITDA, free-cash-flow yield, balance-sheet leverage, replacement cost per ton of capacity, and explicit metal-spread sensitivity. For private investors, the action is in regional and specialty mills and ferroalloy operations, where diligence turns on metallic-input formulas, customer contracts and qualifications, union agreements, environmental liabilities, maintenance capital, power and freight arrangements, and the cost of surviving a low-utilization year; note that no authoritative industry-wide private valuation multiple or transaction median could be established in the research. Verify that a target actually makes steel rather than processing purchased metal — that is the line between this industry and NAICS 3312 [1]. Tickers and detailed valuation work are reserved for the 331110 primer (§4, §10), which is the right place to go for anything actionable — this five-digit level adds no companies or economics beyond its single child.

Outlook: demand is supported by infrastructure spending, manufacturing reshoring, data-center construction, and energy investment, and near-term pricing by the 50% Section 232 rate [15]. Margins are the uncertain half: 640 million tonnes of global excess capacity heading toward 745 million by 2028 [18], volatile scrap, ore, and energy costs, and reversible trade policy can each overwhelm demand growth. The multi-year story remains the shift to lower-carbon electric-arc production, where the EAF route's lower capital intensity and restart flexibility look advantaged — but every producer still has to earn its cost of capital across a full cycle. Full outlook in 331110 (§10).

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Sources

Drawn from the sources of the revised 331110 primer, plus the federal ground-truth statistics carried over from the previous version of this page. Sources [4] and [7] were recorded on the earlier page without links and are listed here without one; every other entry links to the primary source.

1. U.S. Census Bureau, 2022 NAICS Manual, 2022, https://www.census.gov/naics/?details=33&input=33&year=2022 — industry scope and the process-based boundary with NAICS 3312.
2. U.S. Geological Survey, Mineral Commodity Summaries 2026: Iron and Steel, 2026, https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-iron-steel.pdf — 82 Mt raw steel and ~21 Mt pig iron (2025), ~$149B sales value, ~105 Mt capacity, 95 Mt apparent consumption, 13% net import reliance, 99.7% continuously cast, plant and company counts by route, and market shipment shares.
3. U.S. Department of Energy, Iron and Steel Manufacturing, 2026, https://www.energy.gov/cmei/ito/iron-and-steel-manufacturing — EAFs produce 70% of domestic steel; scrap remelting uses less than half the energy of the ore route.
4. U.S. Census Bureau, 2022 Economic Census — receipts $129.8B; CR4 59.5%, CR8 75.1%, CR20 94.4%, CR50 99.7%; HHI 1,071.9; 73 firms for NAICS 331110/33111. (No link recorded.)
5. U.S. Census Bureau, 2021 Annual Survey of Manufactures, 2022, https://www.census.gov/newsroom/press-releases/2022/annual-survey-of-manufactures.html — $118.8B value of shipments, 2021.
6. U.S. Census Bureau, 2020 Annual Survey of Manufactures, 2021, https://www.census.gov/newsroom/press-releases/2021/2020-annual-survey-of-manufactures-data.html — $74.9B value of shipments, 2020.
7. U.S. Census Bureau, County Business Patterns 2023 — employment (78,532), establishments (359), and annual payroll ($9.1B) for NAICS 33111. (No link recorded.)
8. U.S. Census Bureau, NAICS 331110 Industry Profile, 2023, https://data.census.gov/profile/331110_-_Iron_and_steel_mills_and_ferroalloy_manufacturing?codeset=naics~331110 — 359 employer establishments; average employment ~86,000.
9. Nucor Corporation, 2025 Form 10-K, 2026, https://www.sec.gov/Archives/edgar/data/73309/000119312526071575/nue-20251231.htm — steel mills 62% of external sales, 25.271 Mt shipped, utilization 76%→83%, ~$250M 2026 safety and environmental spending.
10. Steel Dynamics Inc., 2025 Form 10-K, 2026, https://www.sec.gov/Archives/edgar/data/1022671/000110465926021395/stld-20251231x10k.htm — steel operations 72% of sales, 13.749 Mt shipped, ~14.0 Mt capacity, metallics 55%–65% of mill cost, $13.413B sales and $1.428B operating income.
11. Cleveland-Cliffs Inc., 2025 Form 10-K, 2026, https://www.sec.gov/Archives/edgar/data/764065/000076406526000025/clf-20251231.htm — 18.8 Mt produced against 20.0 Mt configured capacity, per-ton input ratios, negative 5% steelmaking gross margin, >90% union-represented hourly workforce.
12. United States Steel Corporation, Form 8-K: Completion of Acquisition, 2025, https://www.sec.gov/Archives/edgar/data/1163302/000110465925062586/tm2518973d1_8k.htm
13. Nippon Steel Corporation, Completion of U.S. Steel Acquisition, 2025, https://www.nipponsteel.com/en/newsroom/news/2025/20250618_100.html — closed June 18, 2025.
14. U.S. Department of Energy, Industrial Decarbonization Roadmap, 2022, https://www.energy.gov/sites/default/files/2022-09/Industrial%20Decarbonization%20Roadmap.pdf
15. U.S. Department of Commerce, Section 232 Tariff Summary, 2026, https://www.trade.gov/press-release/what-they-are-saying-president-trump-strengthens-us-steel-aluminum-and-copper — 50% on steel articles, 25% on qualifying derivative articles as of April 2026.
16. U.S. International Trade Commission, Economic Impact of Section 232 and 301 Tariff Actions, 2023, https://www.usitc.gov/press_room/news_release/2023/er0315_63679.htm — imports −24%, steel-product prices +2.4%, domestic production +1.9% over 2018–2021.
17. U.S. Environmental Protection Agency, Integrated Iron and Steel Manufacturing NESHAP, 2025, https://www.epa.gov/stationary-sources-air-pollution/integrated-iron-and-steel-manufacturing-national-emission
18. Organisation for Economic Co-operation and Development, OECD Steel Outlook 2026, 2026, https://www.oecd.org/en/publications/2026/06/oecd-steel-outlook-2026_a79fb861/full-report/international-efforts-to-address-the-steel-crisis-are-intensifying_b6ca4947.html — global excess capacity 640 Mt in 2025, projected 745 Mt by 2028.