Exhibit
4.3


THIS GLOBAL NOTE
IS HELD BY THE DEPOSITARY (AS DEFINED IN THE SUPPLEMENTAL INDENTURE TO THE
INDENTURE GOVERNING THIS NOTE) OR ITS NOMINEE IN CUSTODY FOR THE BENEFIT OF THE
BENEFICIAL OWNERS HEREOF, AND IS NOT TRANSFERABLE TO ANY PERSON UNDER ANY
CIRCUMSTANCES EXCEPT THAT (I) THE TRUSTEE MAY MAKE SUCH NOTATIONS HEREON AS MAY
BE REQUIRED PURSUANT TO ARTICLE III OF THE INDENTURE, (II) THIS GLOBAL NOTE MAY
BE EXCHANGED PURSUANT TO SECTION 3.05 OF THE INDENTURE, (III) THIS GLOBAL NOTE
MAY BE DELIVERED TO THE TRUSTEE FOR CANCELLATION PURSUANT TO SECTION 3.09 OF
THE INDENTURE AND (IV) THIS GLOBAL NOTE MAY BE TRANSFERRED TO A SUCCESSOR
DEPOSITARY WITH THE PRIOR WRITTEN CONSENT OF THE COMPANY OR ANY SUCCESSOR
THERETO.


UNLESS THIS NOTE
IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE OF THE DEPOSITARY (AS DEFINED IN
THE SUPPLEMENTAL INDENTURE TO THE INDENTURE GOVERNING THIS NOTE), TO THE
COMPANY OR ANY SUCCESSOR THERETO OR ITS AGENT FOR REGISTRATION OF TRANSFER,
EXCHANGE, OR PAYMENT, AND ANY CERTIFICATE ISSUED IS REGISTERED IN THE NAME OF
CEDE & CO. OR IN SUCH OTHER NAME AS IS REQUESTED BY AN AUTHORIZED
REPRESENTATIVE OF THE DEPOSITARY (AND ANY PAYMENT IS MADE TO CEDE & CO. OR
TO SUCH OTHER ENTITY AS IS REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF THE DEPOSITARY),
ANY TRANSFER, PLEDGE, OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY
PERSON IS WRONGFUL INASMUCH AS THE REGISTERED OWNER HEREOF, CEDE & CO., HAS
AN INTEREST HEREIN.


UNITED STATES STEEL CORPORATION


	
  No. 1

  	
   

  	
  Principal Amount
  $300,000,000

  
	
   

  	
   

  	
  CUSIP No. 912909AB4

  
	
   

  	
   

  	
  ISIN NO. US912909AB47

  



 


5.65% Senior Notes due 2013


United States
Steel Corporation, a Delaware corporation, for value received, hereby promises
to pay to CEDE & CO., or registered assigns, the principal sum of THREE
HUNDRED MILLION DOLLARS ($300,000,000) on June 1, 2013.


Interest Payment Dates:  June 1 and December 1

Record Dates:  May 15 and November 15

Additional provisions of this Note are set forth on the other side of this
Note.











IN WITNESS WHEREOF, the Corporation has caused this
Instrument to be duly executed.


	
  

  	
  UNITED STATES STEEL CORPORATION

  
	
   

  	
   

  
	
   

  	
  By:

  	
  /s/ L. T. Brockway

  
	
   

  	
  Name:

  	
  L. T. Brockway

  
	
   

  	
  Title:

  	
  Vice President & Treasurer

  



 


 


 


	
  ATTEST:

  	
   

  
	
   

  	
   

  
	
  /s/ J. A. Napoli

  	
   

  
	
  Assistant Secretary

  	
   

  



 


Dated:  May 21,
2007











TRUSTEE CERTIFICATE OF
AUTHENTICATION


This is one of the Notes of the series designated therein referred to in the
within-mentioned Indenture.


	
  

  	
   

  	
  THE BANK OF NEW YORK, as Trustee

  
	
   

  	
   

  	
   

  
	
   

  	
   

  	
   

  
	
   

  	
   

  	
  By:

  	
  /s/ Mary LaGumina

  
	
   

  	
   

  	
   

  	
  Authorized Signatory

  
	
   

  	
   

  	
   

  	
   

  
	
   

  	
   

  	
   

  	
   

  
	
   

  	
   

  	
  Dated: May 21, 2007

  



 















(Reverse of Note)


5.65% Senior
Notes due 2013


1.             Interest.


United States Steel Corporation, a Delaware
corporation (the ”Company and the “Issuer”) promises to pay
interest on the principal amount of this Note at the rate per annum share
above.


The Issuer shall pay accrued interest semiannually on
each June 1 and December 1, commencing on December 1, 2007 or if any such day
is not a Business Day (as defined in the Indenture referred to below), on the
next Business Day.


2.             Method of Payment.


The Issuer shall pay the principal of (and premium, if
any) and interest on the Notes (except defaulted interest) to the Persons who
are the registered Holders at the close of business on the Record Date
immediately preceding the Interest Payment Date even if the Notes are
cancelled, repurchased or redeemed after such Record Date, and on or before
such Interest Payment Date.  Holders must
surrender Notes to a Paying Agent to collect principal payments.  The Issuer shall pay principal and interest
in money of the United States that at the time of payment is legal tender for
payment of public and private debts (“U.S. Legal Tender”).  However, the Issuer may pay principal and
interest by check payable in such U.S. Legal Tender.  The Company may deliver any such interest
payment to the Paying Agent or to a Holder at the Holder’s registered address.


3.             Paying Agent and Registrar.


Initially, the Company will act as Paying Agent and
Security Registrar.  The Company may
appoint and change any Paying Agent, Security Registrar or co-Registrar without
notice to any Holder.  The Company or any
of its domestically incorporated wholly-owned Subsidiaries may act as the
Company Paying Agent.


4.             Indenture.


The Issuer issued the Notes under an Indenture, dated
as of May 21, 2007 (the “Base  Indenture”), between the Issuer and
The Bank of New York, a New York banking corporation (the “Trustee.”),
as supplemented by a Supplemental Indenture, dated as of May 21, 2007, between
the Issuer and The Bank of New York, a New York banking corporation, as Trustee
(the “Supplemental Indenture,” and together with the Base Indenture, the
“Indenture”).  The  terms of the Notes include those stated in the Indenture
and those made part of the Indenture by reference to the Trust Indenture Act of
1939 (15 U.S. C. §§ 77aaa-77bbbb), as in effect on the date of the
Indenture (the “TIA”). 
Capitalized terms used herein and not defined herein have the meanings
ascribed thereto in the Indenture.  The
Notes are subject to all such terms, and Holders are referred to the Indenture
and the TIA for a statement of terms.











The Notes are senior and unsecured obligations of the
Issuer.  The Notes include the Initial
Notes and any Additional Notes actually issued. 
The Initial Notes and any Additional Notes actually issued are treated as
a single class of securities under the Indenture.  The Indenture imposes certain limitations on
the incurrence of Liens and certain sale leaseback transactions with respect to
Principal Property and limits the Company’s ability to consolidate, merge or transfer,
all or substantially all of the Company’s assets.  Each Holder, by accepting a Note, agrees to
be bound by all of the terms and provisions of the Indenture.  Any conflict between this Note and the
Indenture will be governed by the Indenture.


5.             Mandatory Redemption.


If, for any reason, (i) the proposed acquisition of
Lone Star is not completed on or prior to October 1, 2007 or (ii) the
Merger Agreement is terminated on or prior to October 1, 2007, the Company
shall redeem all of the Notes on the Special Mandatory Redemption Date at the
Special Mandatory Redemption Price. 
Notice of a special mandatory redemption shall be mailed promptly after
the occurrence of the event triggering redemption to each Holder at its
registered address.  If funds sufficient
to pay the Special Mandatory Redemption Price (including any accrued and unpaid
interest) of all of the Notes to be redeemed on the Special Mandatory
Redemption Date are deposited with the Paying Agent on or before such Special
Mandatory Redemption Date, and certain other conditions are satisfied, on and
after such Special Mandatory Redemption Date the Notes shall cease to bear
interest.


6.             Optional Redemption.


The Company may redeem the Notes, at its option, at
any time in whole, or from time to time in part, at a price equal to the
greater of:


(i)            100% of the principal amount
of the Notes to be redeemed; or


(ii)           the sum of the present values
of the remaining scheduled payments of principal and interest on the Notes to
be redeemed, exclusive of interest accrued to the date of redemption,
discounted to the date of redemption on a semiannual basis (assuming a 360-day
year consisting of twelve 30-day months) at the applicable Treasury Yield plus
15 basis points, plus accrued interest to the date of redemption.


7.             Notice of Redemption.


The Notes called for redemption become due on the date
fixed for redemption. Notices of redemption shall be mailed by first-class mail
at least 30 but not more than 60 days before the redemption date to each Holder
to be redeemed at its registered address. The notice of redemption for the
Notes shall state the amount to be redeemed. On and after the redemption date,
interest shall cease to accrue on any Notes that are redeemed. If less than all
the Notes of either series are redeemed at any time, the Trustee shall select
Notes on a pro rata basis or by any other method the Trustee deems fair and
appropriate.











8.             Change of Control Repurchase Event.


If a Change of Control Repurchase Event occurs, unless
the Company has exercised its right to redeem the Notes pursuant to the
Indenture, the Company shall be required to make an offer to each Holder to
repurchase all or any part (in excess of $1,000 and in integral multiples of
$1,000) of that Holder’s Notes at a repurchase price in cash equal to 101% of
the aggregate principal amount of the Notes repurchased plus any accrued and
unpaid interest on the Notes repurchased to, but not including, the date of
repurchase. Within 30 days following any Change of Control Repurchase Event or,
at the option of the Company, prior to any Change of Control, but after the
public announcement of the Change of Control, the Company shall mail a notice
to each Holder, with a copy to the Trustee, describing the transaction or
transactions that constitute or may constitute the Change of Control Repurchase
Event and offering to repurchase the Notes on the payment date specified in the
notice, which date shall be no earlier than 30 days and no later than 60 days
from the date such notice is mailed. The notice shall, if mailed prior to the
date of consummation of the Change of Control, state that the offer to purchase
is conditioned on a Change of Control Repurchase Event occurring on or prior to
the payment date specified in the notice. The Company shall comply with the
requirements of Rule 14e-1 under the Exchange Act, and any other securities
laws and regulations thereunder to the extent those laws and regulations are
applicable in connection with the repurchase of the Notes as a result of a
Change of Control Repurchase Event. To the extent that the provisions of any
securities laws or regulations conflict with the Change of Control Repurchase
Event provisions of the Notes, the Company shall comply with the applicable
securities laws and regulations and shall not be deemed to have breached its
obligations under the Change of Control Repurchase Event provisions of the
Notes by virtue of such conflict.


On the repurchase date following a Change of Control
Repurchase Event, the Company shall, to the extent lawful:


(i)            accept for payment all the
Notes or portions of the Notes properly tendered pursuant to its offer;


(ii)           deposit with the Paying Agent
an amount equal to the aggregate purchase price in respect of all the Notes or
portions of the Notes properly tendered; and


(iii)          deliver or cause to be
delivered to the Trustee the Notes properly accepted, together with an officers’
certificate stating the aggregate principal amount of Notes being purchased by
the Company.


The Paying Agent shall promptly mail to each Holder
properly tendered, the purchase price for the Notes, and the Trustee shall
promptly authenticate and mail (or cause to be transferred by book-entry) to
each Holder a new Note equal in principal amount to any unpurchased portion of
any Notes surrendered.


The Company shall not be required to make an offer to
repurchase the Notes upon a Change of Control Repurchase Event if a third party
makes such an offer in the manner, at the times and otherwise in compliance
with the requirements for an offer made by the Company and such third party
purchases all Notes properly tendered and not withdrawn under its offer.











9.             Denominations; Transfer; Exchange.


The Notes are in registered form without coupons in
denominations of principal amount of $1,000 and whole multiples of $1,000.  A Holder may register, transfer or exchange
Notes in accordance with the Indenture. 
The Security Registar may require a Holder, among other things, to
furnish appropriate endorsements or transfer documents and to pay any taxes and
fees required by law or permitted by the Indenture.  The Security Registar need not register the
transfer of or exchange (i) any Notes selected for redemption (except, in the
case of a Note to be redeemed in part, the portion of the Note not to be
redeemed) for a period beginning 15 business days before a selection of Notes
to be redeemed and ending on the date of such selection or (ii) any Notes for a
period beginning on a record date and ending on the next succeeding interest
payment date.


10.           Persons Deemed Owners.


The registered holder of this Note shall be treated as
the owner of it for all purposes.


11.           Unclaimed Money.


If money for the payment of principal or interest
remains unclaimed for one year after the date of payment of principal and
interest, the Trustee or Paying Agent shall pay the money back to the Issuer
without interest thereon upon written request by the Issuer.  After any such payment, Holders entitled to
the money shall look only to the Issuer and not the Trustee for payment.


12.           Defeasance.


Subject to certain conditions set forth in the
Indenture, the Issuer at any time may terminate some or all of its obligations
under the Notes and the Indenture if the Issuer deposits with the Trustee money
or U.S. Government Obligations for the payment of principal of and interest on
the Notes to redemption or maturity, as the case may be.


13.           Amendment, Waiver.


Subject to certain exceptions set forth in the
Indenture, (i) the Indenture or the Notes may be amended with the written
consent of the Holders of a least a majority in principal amount at maturity of
the outstanding Notes and (ii) any default or noncompliance with any provision
may be waived with the written consent of the Holders of a majority in
principal amount at maturity of the outstanding Notes.  Subject to certain exceptions set forth in the
Indenture, without the consent of any Holder, the Issuer and the Trustee may
amend the Indenture or the Notes to cure any ambiguity, omission, defect or
inconsistency, or to provide for uncertificated Notes in addition to or in
place of certificated Notes, or to add guarantees with respect to the Notes or
to secure the Notes, or to add additional covenants of or surrender rights and
powers conferred on the Issuer, or to make any change that does not materially
and adversely affect the rights of any Holder.











14.           Defaults and Remedies.


Under the Indenture, Events of Default include (i) a
failure by the Company to repurchase Notes of such series tendered for
repurchase following the occurrence of a Change of Control Repurchase Event in
conformity with Paragraph 8 hereto and Section 5.03 of the Supplemental
Indenture, (ii) a default in any payment of interest on any Note when due,
continued for 30 days, (iii) a default in the payment of principal of (or
premium, if any) on any Note when due at its Maturity, (iv) a default in the
deposit of any sinking fund payment, when and as due by the terms of the Note
and continuance of such default for a period of 30 days, (v) a default by the
Company in the performance, or breach, of any covenant or warranty contained in
the Indenture for 90 days after notice, (vi) certain events of bankruptcy,
insolvency or reorganization of the Company. 
If an Event of Default occurs and is continuing, the Trustee or the
Holders of at least 25% in aggregate principal amount of the outstanding Notes
may declare all the Notes to be due and payable immediately.


Holders may not enforce the Indenture or the Notes
except as provided in the Indenture.  The
Trustee may refuse to enforce the Indenture or the Notes unless it receives
reasonable indemnity or security. 
Subject to certain limitations, Holders of a majority in principal
amount of the Notes may direct the Trustee in its exercise of any trust or
power.  The Trustee may withhold from
Holders notice of any continuing Default or Event of Default (except a Default
or Event of Default in payment of principal or interest) if it determines that
withholding notice is not opposed to their interest.


15.           Trustee Dealings with the Issuer.


Subject to the terms of the TIA and the Indenture, the
Trustee under the Indenture, in its individual or any other capacity, may
become the owner or pledgee of Notes and may otherwise deal with and collect
obligations amend to it by the Issuer or its Affiliates and may otherwise deal
with the Issuer or its Affiliates with the same rights it would have if it were
not the Trustee.


16.           No Recourse Against Others.


No director, officer, employee, member, incorporator
or stockholder of the Issuer shall have any liability for any obligations of
the Issuer under the Notes or the Indenture or for any claim based on, in
respect of, or by reason of such obligations or their creation.  Each Holder of Notes by accepting a Note
waives and releases all such liability. 
This waiver and release are part of the consideration for issuance of
the Notes.


17.           Authentication.


This Note shall not be valid until an authorized
signature of the Trustee (or an authenticating agent (acting on its behalf)
manually signs the certificate of authentication on the other side of this
Note.


18.           Abbreviations


Customary abbreviations may be used in the name of a
Holder or an assignee, such as: TEN COM (= tenants in common), TEN ENT (=
tenants by the entireties), JT TEN (= joint











tenants with right of survivorship and not as tenants
in common), CUST (= Custodian), and U/G/M/A (= Uniform Gifts to Minors Act).


19.           CUSIP Numbers


Pursuant to a recommendation promulgated by the
Committee on Uniform Security Identification Procedures the Issuer has caused
CUSIP numbers to be printed on the Notes and has directed the Trustee to use
CUSIP numbers in notices of redemption as a convenience to Holders.  No representation is made as to the accuracy
of such numbers either as printed on the Notes or as contained in any notice of
redemption and reliance may be placed only on the other identification numbers
placed thereon.


20.           Governing Law.


THIS NOTE SHALL BE GOVERNED BY AND CONSTRUED IN
ACCORDANCE WITH THE LAWS OF THE STATE OF NEW YORK.















 


ASSIGNMENT FORM


To assign this Note, fill in the form below and have
your signature guaranteed:


I or we assign and
transfer this Note to:


	
  

  
	
   

  
	
   

  



 


(Print or type
name, address and zip code and

social security or tax ID number of assignee)


	
  and irrevocably appoint

  	
   

  



agent to transfer this
Note on the books of the Company.  The
agent may substitute another to act for him.


	
  Dated:

  	
   

  	
   

  	
  Signed:

  	
   

  
	
   

  	
   

  	
   

  	
   

  	
  (Sign exactly as your name appears on the

  other side of this Note)

  



 


	
  Signature Guarantee:

  	
   

  
	
   

  	
   

  



 


(Signature must be guaranteed by a participant in a
recognized Signature Guarantee Medallion Program or other signature guarantor
program reasonably acceptable to the Trustee)











OPTION OF HOLDER TO ELECT
PURCHASE


If you want to elect to have this Note purchased by
the Issuer pursuant to Section 5.03 of the Supplemental Indenture, check the
box  [   
]


If you want to elect to have only part of this Note
purchased by the Issuer pursuant to Section 5.03 of the Supplemental Indenture,
state the amount you elect to have purchased (must be integral multiple of
$1,000):


	
  

  	
   

  	
   

  	
  $

  	
   

  	
   

  
	
   

  	
   

  	
   

  	
   

  	
   

  
	
   

  	
   

  	
   

  	
   

  	
   

  
	
  Dated:

  	
   

  	
   

  	
  Your Signature:

  	
   

  
	
   

  	
   

  	
   

  	
  Sign exactly as your name appears on the face of

  this Note.

  
							



 


	
  Signature Guarantee:

  	
   

  	
   

  
	
  (Signature must be guaranteed by a participant in a

  recognized Signature Guarantee Medallion Program

  or other signature guarantor program reasonably

  acceptable to the Trustee)

  	
   

  



 











SCHEDULE OF
EXCHANGES OF INTERESTS IN THE GLOBAL NOTE


The following increases or decreases in this Global
Note have been made:


	
  Date of

  Exchange

  	
   

  	
  Amount of

  decrease in

  Principal

  Amount of

  this Global

  Note

  	
   

  	
  Amount of

  increase in

  Principal

  Amount of

  this Global

  Note

  	
   

  	
  Principal

  Amount of this

  Global Note

  following such

  decrease or

  increase

  	
   

  	
  Signature of

  authorized

  officer of

  Trustee or

  Notes

  Custodian