United States Steel Corporation
March 5, 2007
Page 2

opinion, I have assumed (a) the authenticity of all original documents and the genuineness of all signatures; (b) the conformity to the originals of all documents submitted to me as copies; (c) the truth, accuracy and completeness of the information, representations and warranties contained in the records, documents, instruments and certificates I have reviewed; (d) the Registration Statement and any amendments thereto (including any post-effective amendments) will have become effective under the Securities Act; (e) any Prospectus Supplement will have been filed with the Securities and Exchange Commission describing the Securities offered thereby; (f) all Securities will be issued and sold in compliance with applicable federal and state securities laws and in the manner stated in the Registration Statement and the applicable Prospectus Supplement; (g) a definitive Underwriting Agreement with respect to any Securities offered will have been duly authorized and validly executed and delivered by the Corporation and the other parties thereto prior to the issuance of the Securities; (h) any securities issuable upon the conversion, exchange, redemption or exercise of any Securities being offered will be duly authorized, created and, if appropriate, reserved for issuance upon such conversion, exchange, redemption or exercise; (i) with respect to shares of Common Stock or Preferred Stock offered, there will be sufficient shares of Common Stock or Preferred Stock authorized under the Corporation’s Certificate of Incorporation, as amended, and not otherwise reserved for issuance; and (j) the Board of Directors of the Corporation, or a duly constituted and acting committee thereof, will have taken all necessary corporate action to approve the issuance and terms of the Securities, the terms of the offering thereof and all related matters.

Based upon the foregoing, I am of the opinion that:

1.

With respect to Debt Securities, when (a) the Trustee is qualified to act as trustee under the applicable Indenture, (b) the applicable Indenture, and any applicable supplement thereto, has been duly authorized and validly executed and delivered by the Company and the Trustee, (c) the applicable Indenture has been duly qualified under the Trust Indenture Act of 1939, and (d) the Debt Securities have been duly executed, issued, delivered and authenticated in accordance with the terms of the Indenture and applicable Underwriting Agreement against the receipt of the requisite consideration therefor, the Debt Securities will constitute the legal, valid and binding obligations of the Corporation enforceable against it in accordance with the terms thereof.

2.

With respect to Common Stock, when the shares of Common Stock have been issued and delivered in accordance with the applicable Underwriting Agreement against receipt of the requisite consideration therefor, such shares of Common Stock will be validly issued, fully paid and non-assessable.

3.

With respect to Preferred Stock, when (a) the applicable Certificate of Designation for the Preferred Stock to be issued has been duly filed with the Office of the Secretary of State of the State of Delaware, and (b) the shares of Preferred Stock have been issued and delivered in accordance with the applicable Underwriting Agreement against receipt of the requisite consideration therefor, such shares of Preferred Stock will be validly issued, fully paid and non-assessable.