ϳԹ

Exhibit 21
UNITED STATES STEEL CORPORATION
SUBSIDIARIES AND JOINT VENTURES AS OF DECEMBER 31, 2023
Company Name
Jurisdiction
Big River Steel International, Inc.
Delaware
Chisholm Coal LLC
Kentucky
Chrome Deposit Corporation
Indiana
Compagnie de Gestion de Mifergui- Nimba, LTEE
Delaware
Cygnus Mines Limited
Canada
Double G Coatings, Inc.
Delaware
Double G Coatings Company, L.P.
Delaware
Essex Minerals Company
New Jersey
Fairfield Primary Operations, LLC
Texas
GCW/ϳԹ Energy, LLC
Illinois
Grant Assurance Corporation
Vermont
Kanawha Coal LLC
West Virginia
Orinoco Mining Company
Delaware
Perdido Land Development Co., Inc.
Delaware
Pitcal Pipe, LLC
Delaware
Preserve Village Developers, LLC
Delaware
Stelco Holding Company
Delaware
Ontario Coal Company
Delaware
Ontario Eveleth Company
Minnesota
Ontario Hibbing Company
Minnesota
Hibbing Development Company
Minnesota
Hibbing Taconite Company
Minnesota
Stelco Coal Company
Pennsylvania
Stelco Erie Corporation
Delaware
Ontario Tilden Company
Michigan
Swan Point Yacht & Country Club, Inc.
Delaware
Timber Wolf Land, LLC
Delaware
U. S. Steel China, LLC
Delaware
U. S. Steel Holdco LLC
Delaware
Big River Steel Holdings LLC
Delaware
BRS Intermediate Holdings LLC
Delaware
Big River Steel LLC
Delaware
BRS Finance Corp
Delaware
Exploratory Ventures, LLC
Delaware
BRS Stock Holdco LLC
Delaware
Big River Steel Corp
Delaware
U. S. Steel Blocker LLC
Delaware
U. S. Steel Holdings, Inc.
Delaware
U. S. Steel Global Holdings I B.V.
Netherlands
U. S. Steel Global Holdings VI B.V.
Netherlands
U. S. Steel Košice, s.r.o. (ϳԹK)
Slovakia
Tubular s.r.oSlovakia
U. S. Steel Europe - France S.A.
France
U.S. Steel Košice - SBS, s.r.o.
Slovakia
U. S. Steel Europe - Germany GmbH
Germany
U. S. Steel Global Holdings II, B.V.
Netherlands
U. S. Steel Canada Limited Partnership
Canada
U. S. Steel LRD Canada North Inc.
Canada
U. S. Steel Mining Company, LLC
Alabama



UNITED STATES STEEL CORPORATION
SUBSIDIARIES AND JOINT VENTURES AS OF DECEMBER 31, 2023

U. S. Steel Timber Company, LLC
Alabama
U. S. Steel Tubular Products, LLCDelaware
Lone Star Steel Holdings, Inc.
Delaware
Lone Star Steel Holdings II, Inc.
Oklahoma
U. S. Steel Tubular Products Middle East DMCC
Dubai, UAE
U. S. Steel Oilwell Services, LLC
Delaware
Patriot Premium Threading Services, LLC
Delaware
ϳԹ Construction Products, LLC
Delaware
U. S. Steel Tubular Products Canada ULC
Canada
Zinklahoma, Inc.
Delaware
U. S. Steel Tubular Products Holdings, LLC
Texas
U. S. Steel Seamless Tubular Operations, LLC
Texas
Star Brazil US, LLC 2
Texas
Star Brazil US, LLC 1Texas
Lone Star Brazil Holdings 1 Ltda.Brazil
UEC Technologies, LLC
Pennsylvania
USX Engineers and Consultants
Delaware
UEC Sail Information Technology, LTD.
India
United States Steel International, Inc.
New Jersey
United States Steel Export Company de Mexico, S.R.L. de C.V.
Mexico
United States Steel International de Mexico, S.R.L. de C. V.
Mexico
ϳԹ Galvanizing, Inc.
Delaware
PRO-TEC Coating Company, LLC
Delaware
PRO-TEC Coating Company, Inc.
Ohio
ϳԹ International Services, LLC
Delaware
ϳԹ Lakeside, LLC
Delaware
Chicago Lakeside Development, LLC
Delaware
CLD Parcel 14 LLCDelaware
CLD Adjoining Residential Parcels LLCDelaware
ϳԹ Oilwell Supply Co., LTD.
Delaware
ϳԹ Oilwell Tubular, Inc.
Delaware
ϳԹ Portfolio Delaware, Inc.
Delaware
ϳԹ Ventures, LLC
Delaware
ϳԹ WSP, LLC
Delaware
Worthington Specialty Processing
Michigan
ProCoil Company, LLC
Delaware
ϳԹ-UPI, LLC
Delaware
USX International Sales Company, Inc.
Barbados
Ventures RE Company I, LLCDelaware
Ventures RE Company II, LLCDelaware
Warrior & Gulf Navigation LLCAlabama