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                                                                     Exhibit 3.1

                     RESTATED CERTIFICATE OF INCORPORATION
                                      OF
                                CLARK USA, INC.


     Clark USA, Inc. (the "Corporation"), a corporation duly organized and
existing under and by virtue of the General Corporation Law of the State of
Delaware, does hereby certify:

     1.  The name under which the Corporation was originally incorporated was
AOC Holdings, Inc.

     2.  The Corporation's original Certificate of Incorporation was filed with
the Secretary of State of Delaware on October 24, 1988.  Certificates of
Amendment to the Certificate of Incorporation were filed with the Secretary of
State of Delaware on November 15, 1988, November 22, 1988, September 25, 1990,
February 1, 1993 and September 19, 1994.

     3.  Pursuant to Sections 242 and 245 of the General Corporation Law of the
State of Delaware, this Restated Certificate of Incorporation restates and
integrates and further amends the provisions of the Amended Certificate of
Incorporation of the Corporation.

     4.  The text of the Restated Certificated of Incorporation as heretofore
amended is restated and further amended to read in its entirety as follows:

          FIRST: The name of the Corporation is CLARK USA, INC. (the
     "Corporation").

          SECOND: The address of its registered office in the State of Delaware
     is 1209 Orange Street, in the City of Wilmington, County of New Castle. The
     name of its registered agent at such address is The Corporation Trust
     Company.

          THIRD: The purpose of the Corporation is to engage in any lawful act
     or activity for which corporations may be organized under the General
     Corporation Law of Delaware. The Corporation is to have perpetual
     existence.

          FOURTH: (a) Effective as of the close of business on the date on which
     this Restated Certificate of Incorporation shall have been filed, every
     229,603 outstanding shares of Common Stock outstanding prior to such
     effective date shall be deemed to be converted into and reconstituted as
     one (1) share of Common Stock.

          b)  Thereafter, the Corporation shall be authorized to issue one class
     of shares of stock to be designated "Common Stock" and the total number of
     authorized shares of Common Stock shall be One Thousand (1,000) and each
     such share shall have a par value of One Cent ($0.01).  The Corporation
     shall have no preferred stock.

          FIFTH: In furtherance and not in limitation of the powers conferred by
     statute, the board of directors is expressly authorized to make, alter,
     repeal and amend the By-laws of the Corporation.
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          SIXTH: The number of directors of the Corporation shall be fixed by
     the By-laws of the Corporation, as they may be amended from time to time.

          SEVENTH: Elections of directors need not be by written ballot unless
     the bylaws of the corporation shall so provide.

          EIGHTH:  The Corporation reserves the right to amend, alter, change or
     repeal any provision contained in this Certificate of Incorporation, in the
     manner now or hereafter prescribed by statute, and all rights conferred
     upon stockholders herein are granted subject to this reservation.

          NINTH: To the fullest extent permitted by the Delaware General
     Corporation Law as the same exists or may hereafter be amended, a director
     of the Corporation shall not be liable to the Corporation or its
     stockholders for monetary damages for breach of fiduciary duty as a
     director. If the Delaware General Corporation Law is amended after the date
     of the filing of this Restated Certificate of Incorporation to authorize
     corporate action further eliminating or limiting the personal liability of
     directors, then the liability of a director of the corporation shall be
     eliminated or limited to the fullest extent permitted by the Delaware
     General Corporation Law, as so amended from time to time. No repeal or
     modification of this Article Nine by the stockholders shall adversely
     affect any right or protection of a director of the corporation existing by
     virtue of this Article Nine at the time of such repeal or modification.

          TENTH: Holders of stock shall not have pre-emptive rights to subscribe
     for any new or increased shares of stock of the Corporation.

     5.  This Restated Certificated of Incorporation was duly adopted by the
Board of Directors in accordance with the provisions of Section 141, 242 and 245
of the Delaware General Corporation Law and was duly adopted by the written
consent of the stockholders in accordance with the provisions of Sections 228,
242 and 245 of the Delaware General Corporation Law.

     IN WITNESS WHEREOF, said CLARK USA, INC. has caused this Restated
Certificate of Incorporation to be signed by Paul D. Melnuk, its President and
Chief Executive Officer, and attested by Patrick F. Heider, its Secretary, this
28th day of December, 1994.

                                       CLARK USA, INC.

                                       By:  /s/  Paul D. Melnuk
                                          -------------------------------------
                                          Paul D. Melnuk
                                          President and Chief Executive Officer
[SEAL]

ATTEST:

By:  /s/  Patrick F. Heider
   ---------------------------
     Patrick F. Heider
     Secretary

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