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                                                                      EXHIBIT 24


                                POWER OF ATTORNEY

       WHEREAS, AMEREN CORPORATION, a Missouri corporation (herein referred to
as the "Company"), is required to file with the Securities and Exchange
Commission, under the provisions of the Securities Exchange Act of 1934, as
amended, its annual report on Form 10-K for the year ended December 31, 1999;
and

       WHEREAS, each of the below undersigned holds the office or offices in
the Company set opposite his or her name;

       NOW, THEREFORE, each of the undersigned hereby constitutes and appoints
Charles W. Mueller and/or Donald E. Brandt and/or Steven R. Sullivan the true
and lawful attorneys-in-fact of the undersigned, for and in the name, place and
stead of the undersigned, to affix the name of the undersigned to said Form 10-K
and any amendments thereto, and, for the performance of the same acts, each with
power to appoint in their place and stead and as their substitute, one or more
attorneys-in-fact for the undersigned, with full power of revocation; hereby
ratifying and confirming all that said attorneys-in-fact may do by virtue
hereof.

       IN WITNESS WHEREOF, the undersigned have hereunto set their hands this
11th day of February 2000:


                                                               
Charles W. Mueller, Chairman, President,
       Chief Executive Officer and Director
       (Principal Executive Officer)                                     /s/ Charles W. Mueller
                                                                   ----------------------------------------------

William E. Cornelius, Director                                           /s/ William E. Cornelius
                                                                   ----------------------------------------------

Clifford L. Greenwalt, Director                                          /s/ Clifford L. Greenwalt
                                                                   ----------------------------------------------

Thomas A. Hays, Director                                                 /s/ Thomas A. Hays
                                                                   ----------------------------------------------

Richard A. Liddy, Director                                               /s/ Richard A. Liddy
                                                                   ----------------------------------------------

Gordon R. Lohman, Director                                               /s/ Gordon R. Lohman
                                                                   ----------------------------------------------

Richard A. Lumpkin, Director                                             /s/ Richard A. Lumpkin
                                                                   ----------------------------------------------

John Peters MacCarthy, Director                                          /s/ John Peters MacCarthy
                                                                   ----------------------------------------------

Hanne M. Merriman, Director
                                                                   ----------------------------------------------

Paul L. Miller, Jr., Director                                            /s/ Paul L. Miller, Jr.
                                                                   ----------------------------------------------

Robert H. Quenon, Director                                               /s/ Robert H. Quenon
                                                                   ----------------------------------------------

Harvey Saligman, Director                                                /s/ Harvey Saligman
                                                                   ----------------------------------------------

Janet McAfee Weakley, Director                                           /s/ Janet McAfee Weakley
                                                                   ----------------------------------------------

James W. Wogsland, Director
                                                                   ----------------------------------------------

Donald E. Brandt, Senior Vice President
       (Principal Financial Officer)                                     /s/ Donald E. Brandt
                                                                   ----------------------------------------------

Warner L. Baxter, Vice President and Controller
       (Principal Accounting Officer)                                    /s/ Warner L. Baxter
                                                                   ----------------------------------------------





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                                                                      EXHIBIT 24


STATE OF MISSOURI        )
                         )  SS.
CITY OF ST. LOUIS        )

       On this 11th day of February, 2000, before me, the undersigned Notary
Public in and for said State, personally appeared the above-named officers and
directors of Ameren Corporation, known to me to be the persons described in and
who executed the foregoing power of attorney and acknowledged to me that they
executed the same as their free act and deed for the purposes therein stated.

       IN TESTIMONY WHEREOF, I have hereunto set my hand and affixed my official
seal.


                                                /s/ K. A. Bell
                                    ----------------------------------------
                                                 K. A. BELL
                                           Notary Public - Notary Seal
                                               STATE OF MISSOURI
                                               St. Louis County
                                    My Commission Expires:  October 13, 2002