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            As filed with the Securities and Exchange Commission on July 5, 2001

                                                      Registration No. 033-57997

                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

                       ----------------------------------

                         POST EFFECTIVE AMENDMENT NO. 1
                                       TO
                                    FORM S-3
                             REGISTRATION STATEMENT
                        UNDER THE SECURITIES ACT OF 1933

                       ----------------------------------

                                 USX CORPORATION
             (Exact name of Registrant as Specified in Its Charter)


            DELAWARE                                            25-0996816
  (State or Other Jurisdiction                               (I.R.S. Employer
of Incorporation or Organization)                         Identification Number)


                                600 Grant Street
                            Pittsburgh, PA 15219-4776
                                 (412) 433-1121
          (Address, Including Zip Code, and Telephone Number, Including
              Are Code, of Registrants Principal Executive Offices)


                                 Dan D. Sandman
              General Counsel, Secretary and Senior Vice President-
                        Human Resources & Public Affairs
                                 USX Corporation
                                600 Grant Street
                            Pittsburgh, PA 15219-4776
                                 (412) 433-1121
            (Name, Address, Including Zip Code, and Telephone Number,
                   Including Area Code, of Agent For Service)

         Approximate date of commencement of proposed sale to public: not
applicable.

         If any of the securities being registered on this form are to be
offered pursuant to dividend or interest reinvestment plans, please check the
following box. [ ]

         If any of the securities being registered on this Form are to be
offered on a delayed or continuous basis pursuant to Rule 415 under the
Securities Act of 1933, other than securities offered only in connection with
dividend or interest reinvestment plans, check the following box. [x]

         If this Form is filed to register additional securities for an offering
pursuant to Rule 462(b) under the Securities Act, please check the following box
and list the Securities Act registration statement number of the earlier
effective registration statement for the same offering. [ ] _________________

         If this Form is a post-effective amendment filed pursuant to Rule
462(c) under the Securities Act, check the following box and list the Securities
Act registration statement number of the earlier effective registration
statement for the same offering. [ ] _________________

         If delivery of the prospectus is expected to be made pursuant to Rule
434, please check the following box. [ ]


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                                EXPLANATORY NOTE

         This Post-Effective Amendment No. 1 (the "Amendment") to the
Registration Statement on Form S-3 (Registration No. 033-57997) (the
"Registration Statement") of USX Corporation, a Delaware corporation ("Old
USX"), is being filed by USX Corporation(formerly USX Holdco, Inc.), a Delaware
corporation (the "Company"), pursuant to Rule 414 under the Securities Act of
1933, as amended (the "Securities Act"), to reflect the adoption by Old USX of a
holding company form of organizational structure. The holding company
organizational structure was implemented in accordance with Section 251(g) of
the Delaware General Corporation Law (the "DGCL") pursuant to a Holding Company
Reorganization Agreement, dated as of July 1, 2001 (the "Reorganization
Agreement"), by and among the Company, Old USX, and United States Steel LLC, a
Delaware limited liability company and wholly owned subsidiary of the Company
("SteelCo").

         Pursuant to the terms and subject to the conditions of the
Reorganization Agreement and in accordance with Section 251(g) of the DGCL and
Section 18-209 of the Delaware Limited Liability Company Act, effective on July
2, 2001, Old USX was merged with and into SteelCo (the "Reorganization Merger").
At the effective time of the Reorganization Merger, SteelCo continued as the
surviving entity and as a wholly owned Subsidiary of USX and the separate
corporate existence of Old USX ceased in accordance with the DGCL. In the
Reorganization Merger: (i) each share of Old USX-Marathon Group Common Stock,
par value $1.00 per share ("Old USX-Marathon Group Common Stock") issued and
outstanding or held in treasury was automatically converted into one share of
the Company's Marathon Group Common Stock, par value $1.00 per share ("New
Marathon Group Common Stock"), (ii) each share of Old USX-U. S. Steel Group
Common Stock, par value $1.00 per share ("Old USX-U. S. Steel Group Common
Stock") issued and outstanding or held in treasury was automatically converted
into one share of the Company's U. S. Steel Group Common Stock, par value $1.00
per share ("New U. S. Steel Group Common Stock"), and (iii) each share of Old
USX 6.50% Cumulative Convertible Preferred Stock, no par value, issued and
outstanding or held in treasury was automatically converted into one share of
6.50% Cumulative Convertible Preferred Stock, no par value, of the Company.

         Additionally, (i) each outstanding option to purchase Old USX-Marathon
Common Stock and Old USX-U. S. Steel Group Common Stock issued pursuant to the
1990 Stock Plan was assumed by USX and now represents an option to purchase,
upon the same terms and conditions, an identical number of shares of New
Marathon Group Common Stock and New U. S. Steel Group Common Stock,
respectively, (ii) each outstanding restricted share of Old USX-Marathon Common
Stock and Old USX-U. S. Steel Group Common Stock was automatically converted
into a restricted share of New Marathon Group Common Stock and New U. S. Steel
Group Common Stock, respectively, and (iii) each outstanding stock appreciation
right relating to Old USX-Marathon Common Stock and Old USX-U. S. Steel Group
Common Stock issued pursuant to the 1990 Stock Plan was assumed by USX and now
represents a stock appreciation right relating to New Marathon Group Common
Stock and New U. S. Steel Group Common Stock, respectively.

           In accordance with Rule 414 under the Securities Act, the Company, as
the successor issuer to Old USX, hereby expressly adopts Registration Statement
No. 033-57997 on Form S-3 as its own for all purposes of the Securities Act and
the Securities Exchange Act of 1934, as amended (the "Exchange Act").

           The applicable registration fees were paid at the time of the
original filing of the Registration Statement.


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                                   SIGNATURES



         Pursuant to the requirements of the Securities Act of 1933, as amended,
the Registrant certifies that it has reasonable grounds to believe that it meets
all of the requirements for filing on Form S-3 and has duly caused this
Post-Effective Amendment No. 1 to be signed on its behalf by the undersigned,
thereunto duly authorized, in the City of Pittsburgh, State of Pennsylvania, on
July 5, 2001.


                                   USX CORPORATION

                                   By: /s/ Larry G. Schultz
                                      --------------------------------------
                                      Name:  Larry G. Schultz
                                      Title: Vice President - Accounting


         Pursuant to the requirements of the Securities Act of 1933, as amended,
this Post-Effective Amendment No. 1 to the Form S-3 Registration Statement has
been signed below by the following persons in the capacities indicated on July
5, 2001.



NAME                                           TITLE

                    *                          Chairman of the Board & Chief
------------------------------------------     Executive Officer and Director
            Thomas J. Usher

                    *                          Vice Chairman & Chief Financial
------------------------------------------     Officer and Director
          Robert M. Hernandez

         /s/ Larry G. Schultz                  Vice President - Accounting
------------------------------------------
           Larry G. Schultz

                   *                           Director
------------------------------------------
           Neil A. Armstrong

                   *                           Vice Chairman and Director
------------------------------------------
       Clarence P. Cazalot, Jr.

                   *                           Director
------------------------------------------
             J. Gary Cooper

                   *                           Director
------------------------------------------
           Charles A. Corry

                   *                           Director
------------------------------------------
         Shirley Ann Jackson

                   *                           Director
------------------------------------------
           Charles R. Lee

                   *                           Director
------------------------------------------
             Paul E. Lego

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NAME                                            TITLE


                   *                            Director
------------------------------------------
         John F. McGillicuddy

                   *                            Director
------------------------------------------
          Seth E. Schofield

                   *                            Director
------------------------------------------
              John W. Snow

                   *                            Director
------------------------------------------
           Douglas C. Yearley


* By: /s/ Larry G. Schultz
------------------------------------------
     Larry G. Schultz, attorney-in-fact



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                                  EXHIBIT INDEX


Exhibit No.                Description
-----------                -----------

24                         Powers of Attorney