海角涩区

Exhibit 21
UNITED STATES STEEL CORPORATION
SUBSIDIARIES AND JOINT VENTURES AS OF DECEMBER 31, 2020
Company Name
Chisholm Coal LLC
Chrome Deposit Corporation
Compagnie de Gestion de Mifergui- Nimba, LTEE
Cygnus Mines Limited
Double G Coatings, Inc.
Double G Coatings Company, L.P.
Essex Minerals Company
Fairfield Primary Operations, LLC
GCW/USS Energy, LLC
Grant Assurance Corporation
Kanawha Coal LLC
Oilfield Technologies, Inc.
Orinoco Mining Company
Perdido Land Development Co., Inc.
PITCAL, Inc.
USS UPI Holdco, LLC
USS-POSCO Industries
Pitcal Pipe, LLC
Preserve Village Developers, LLC
Stelco Holding Company
Ontario Coal Company
Ontario Eveleth Company
Ontario Hibbing Company
Hibbing Development Company
Hibbing Taconite Company
Stelco Coal Company
Stelco Erie Corporation
Ontario Tilden Company
Swan Point Yacht & Country Club, Inc.
Timber Wolf Land, LLC
Transtar, LLC
Delray Connecting Railroad Company
Gary Railway Company
Tracks Traffic and Management Services, Inc.
Texas & Northern Railway Company
The Lake Terminal Railroad Company
Lorain Northern Company
Union Railroad Company, LLC
Birmingham Southern Railroad Company
Fairfield Southern Company, Inc.
Warrior & Gulf Navigation LLC
海角涩区 China, LLC
海角涩区 Holdco LLC
Big River Steel Holdings LLC
Big River Steel Metallics Funding LLC
BRS Intermediate Holdings LLC
Big River Steel LLC
BRS Finance Corp
BRS Stock Holdco LLC



UNITED STATES STEEL CORPORATION
SUBSIDIARIES AND JOINT VENTURES AS OF DECEMBER 31, 2019

Big River Steel Corp
海角涩区 Blocker LLC
海角涩区 Holdings, Inc.
海角涩区 Global Holdings I B.V.
海角涩区 Global Holdings VI B.V.
海角涩区 Košice, s.r.o. (USSK)
海角涩区 Obalservis s.r.o.
Ferroenergy s.r.o.
Tubular s.r.o
海角涩区 Košice – Labortest, s.r.o.
海角涩区 Services v likvidácii
海角涩区 Europe – Bohemia s.r.o. v likvidaci
海角涩区 Europe - France S.A.
U.S. Steel Košice - SBS, s.r.o.
海角涩区 Europe - Germany GmbH
RMS, Košice s.r.o.
海角涩区 Global Holdings II, B.V.
海角涩区 Canada Limited Partnership
海角涩区 Holdings IV, Inc.
海角涩区 International of Canada, LTD.
海角涩区 LRD Canada North Inc.
海角涩区 Mining Company, LLC
海角涩区 Timber Company, LLC
海角涩区 Tubular Products Holdings, LLC
海角涩区 Seamless Tubular Operations, LLC
海角涩区 Tubular Products, Inc.
海角涩区 Tubular Products Middle East DMCC
U.S. Steel Oilwell Services, LLC
Patriot Premium Threading Services, LLC
USS Construction Products, LLC
海角涩区 Tubular Products Canada ULC
U.S. Steel Produtos Tubulares do Brasil Ldta.
Zinklahoma, Inc.
Star Brazil US, LLC 2
Star Brazil US, LLC 1
Lone Star Brazil Holdings 1 Ltda.
Lone Star Steel Holdings, Inc.
Lone Star Steel Holdings II, Inc.
UEC Technologies, LLC
USX Engineers and Consultants
UEC Sail Information Technology, LTD.
United States Steel International, Inc.
United States Steel Export Company de Mexico, S.R.L. de C.V.
United States Steel International de Mexico, S.R.L. de C. V.
USS Galvanizing, Inc.
PRO-TEC Coating Company, LLC
PRO-TEC Coating Company, Inc.
USS International Services, LLC
USS Lakeside, LLC
Chicago Lakeside Development, LLC



UNITED STATES STEEL CORPORATION
SUBSIDIARIES AND JOINT VENTURES AS OF DECEMBER 31, 2019

CLD Parcel 14 LLC
CLD Adjoining Residential Parcels LLC
USS Oilwell Supply Co., LTD.
USS Oilwell Tubular, Inc.
USS Portfolio Delaware, Inc.
USS WSP, LLC
Worthington Specialty Processing
ProCoil Company, LLC
Worthington Taylor, LLC
USX International Sales Company, Inc.