EXHIBIT 99.12
                            United States Steel LLC
                             to be converted into
                        United States Steel Corporation

                              Offers to Exchange

     10% Senior Quarterly Income Debt Securities (SQUIDSSM) due 2031

         for the following securities (the "Outstanding Securities"):

        6.50% Cumulative Convertible Preferred Stock of USX Corporation
                            (CUSIP No. 902905 1819)

   6.75% Convertible Quarterly Income Preferred Securities (QUIPSSM) of USX
                                Capital Trust I
                            (CUSIP No. 903339 E201)

 8.75% Cumulative Monthly Income Preferred Shares, Series A (MIPS(R)), of USX
                                  Capital LLC
                            (CUSIP No. P96460 1031)

 EACH OF THE EXCHANGE OFFERS AND WITHDRAWAL RIGHTS WILL EXPIRE AT 5:00 P.M.,
 NEW YORK CITY TIME, ON DECEMBER 7, 2001, UNLESS EARLIER TERMINATED OR
 EXTENDED BY UNITED STATES STEEL LLC.


                                                          November  , 2001


To Our Clients:

  United States Steel LLC (the "Company"), which is currently a wholly owned
subsidiary of USX Corporation, is offering to exchange:

  .  $50 principal amount of its 10% Senior Income Debt Securities due 2031
     ("SQUIDS"), for each validly tendered and accepted share of 6.50%
     Cumulative Convertible Preferred Stock of USX Corporation ("6.50%
     Preferred Stock"), plus a cash payment for accrued but unpaid dividends;


  .  $50 principal amount of SQUIDS, for each validly tendered and accepted
     6.75% Convertible Quarterly Income Preferred Security of USX Capital
     Trust I ("6.75% QUIPS"), plus a cash payment for accrued but unpaid
     distributions; and


  .  $25 principal amount of SQUIDS, for each validly tendered and accepted
     8.75% Cumulative Monthly Income Preferred Share, Series A, of USX
     Capital LLC ("8.75% MIPS"), plus a cash payment for accrued but unpaid
     dividends.


  The exchange offers are made on the terms and are subject to the conditions
set forth in the Company's prospectus dated November 5, 2001 (the
"Prospectus"), and the accompanying Letters of Transmittal, including the
minimum condition that at least $150 million principal amount of SQUIDS, in
the aggregate, are issued in the exchange offers. The Company will accept up
to a maximum face amount of (i) $77 million of 6.50% Preferred Stock, (ii)
$127 million of 6.75% QUIPS and (iii) $161 million of 8.75% MIPS in the
exchange offers. The Company reserves the right to extend, amend or terminate
the exchange offers.

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SQUIDSSM and QUIPSSM are service marks and MIPS(R) is a registered trademark
  of Goldman, Sachs & Co.


  The enclosed Prospectus is being forwarded to you as the beneficial owner of
Outstanding Securities held by us for your account but not registered in your
name. The accompanying Letter of Transmittal and Notice of Guaranteed Delivery
are furnished to you for informational purposes only and may not be used by
you to tender Outstanding Securities held by us for your account. A tender of
such Outstanding Securities may be made only by us as the registered holder
and only pursuant to your instructions.

  Accordingly, we request instructions as to whether you wish us to tender and
deliver the Outstanding Securities held by us for your account. If you wish to
have us do so, please so instruct us by completing, executing and returning to
us the instruction form that appears below.

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                                 INSTRUCTIONS

  The undersigned acknowledge(s) receipt of your letter and the enclosed
materials referred to therein relating to United States Steel's exchange offer
with respect to the 6.50% Cumulative Convertible Preferred Stock (the "6.50%
Preferred Stock") of USX Corporation (CUSIP No. 902905 1819), the 6.75%
Convertible Quarterly Income Preferred Securities (the "6.75% QUIPS") of USX
Capital Trust I (CUSIP No. 903339 E201), and the 8.75% Cumulative Monthly
Income Preferred Shares, Series A (the "8.75% MIPS"), of USX Capital LLC
(CUSIP No. P96460 1031).

  This will instruct you to tender all of the Outstanding Securities of the
series indicated below held by you for the account of the undersigned pursuant
to the terms and conditions set forth in the Prospectus, dated November 5,
2001, and the related Letters of Transmittal.


     6.50% Preferred Stock           TENDER [_]

     6.75% QUIPS                     TENDER [_]

     8.75% MIPS                      TENDER [_]

                                          _____________________________________
                                          Signature(s)

                                          _____________________________________
                                          Please print name(s)

                                          _____________________________________
                                          Address

                                          _____________________________________
                                          Zip Code

                                          _____________________________________
                                          Area Code and Telephone No.

                                          _____________________________________
                                          Tax Identification or Social
                                           Security No.

                                          _____________________________________
                                          My Account Number with You

                                          _____________________________________
                                          Date


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