Document:

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                                                                     Exhibit 4.2

                             SUPPLEMENTAL INDENTURE

                       TO INDENTURE DATED AUGUST 15, 1997

         THIS SUPPLEMENTAL INDENTURE dated as of August 30, 2001, is delivered
pursuant to Section 4.11 of the Indenture dated as of August 15, 1997 (as
heretofore or hereafter modified and supplemented and in effect from time to
time, the "1997 Indenture") among OUTDOOR COMMUNICATIONS, INC., a Delaware
corporation, certain of its subsidiaries (the "Guarantors") and FIRST UNION
NATIONAL BANK, a national banking corporation, as Trustee (the "Trustee") (all
terms used herein without definition having the meanings ascribed to them in the
1997 Indenture).

         The undersigned hereby agrees that:

         1. The undersigned is a Guarantor under the 1997 Indenture with all of
the rights and obligations of the Guarantors thereunder.

         2. The undersigned has granted, ratified and confirmed, in the form and
substance of Exhibit B to the 1997 Indenture, the Guarantee provided for by
Article XI of the 1997 Indenture.

         3. The undersigned hereby represents and warrants that the
representations and warranties set forth in the 1997 Indenture, to the extent
relating to the undersigned as Guarantor, are correct on and as of the date
hereof.

         4. All notices, requests and other communications provided for in the
1997 Indenture should be delivered to the undersigned at the following address:

                  Keith A. Istre
                  Vice President - Finance and
                  Chief Financial Officer
                  Lamar Media Corp. and its Subsidiaries
                  5551 Corporate Blvd.
                  Baton Rouge, LA 70808

         5. A counterpart of this Supplemental Indenture may be attached to any
counterpart of the 1997 Indenture.

         6. This Supplemental Indenture shall be governed by and construed in
accordance with the internal laws of the State of New York.

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         IN WITNESS WHEREOF, the undersigned have caused this Supplemental
Indenture to be duly executed as of the day and year first above written.

                                      Guarantor:

                                      Maine Logos, LLC,
                                      a Maine limited liability company

                                      By: Interstate Logos, L.L.C.
                                      Its: Managing Member

                                      By: Lamar Media Corp.
                                      Its: Managing Member

                                      By:  /s/ Keith A. Istre
                                         ---------------------------------------
                                            Keith A. Istre
                                            Vice President - Finance and Chief
                                            Financial Officer
Attest:

By:      /s/ James R. McIlwain
   -------------------------------
     James R. McIlwain, Secretary

Accepted:

FIRST UNION NATIONAL BANK, as Trustee

By:  /s/ James Long
   -------------------------------
Title:   Assistant Vice President
   -------------------------------

                                       2<PAGE>

                                                                     Exhibit 4.3

                             SUPPLEMENTAL INDENTURE

                                       OF

                                    GUARANTOR

         THIS SUPPLEMENTAL INDENTURE dated as of August 30, 2001, is delivered
pursuant to Section 10.04 of the Indenture dated as of September 25, 1997 (as
heretofore or hereafter modified and supplemented and in effect from time to
time, the "Indenture") among LAMAR MEDIA CORP., a Delaware corporation, certain
of its subsidiaries ("Guarantors") and STATE STREET BANK AND TRUST COMPANY, a
Massachusetts banking corporation, as Trustee ("Trustee") (all terms used herein
without definition having the meanings ascribed to them in the Indenture).

         The undersigned hereby agree that:

         1. The undersigned is a Guarantor under the Indenture with all of the
rights and obligations of Guarantors thereunder.

         2. The undersigned hereby grants, ratifies and confirms the guarantee
provided for by Article Ten of the Indenture to guarantee unconditionally,
jointly and severally with the other Guarantors, to each Holder of a Note
authenticated and delivered by the Trustee, and to the Trustee on behalf of such
Holder, the due and punctual payment of the principal of (and premium, if any)
and interest on such Note when and as the same shall become due and payable.

         3. The undersigned hereby represents and warrants that the
representations and warranties set forth in the Indenture, to the extent
relating to the undersigned as Guarantor, are correct on and as of the date
hereof.

         4. All notices, requests and other communications provided for in the
Indenture should be delivered to the undersigned at the address specified in
Section 12.02 of the Indenture.

         5. A counterpart of this Supplemental Indenture may be attached to any
counterpart of the Indenture.

         6. This Supplemental Indenture shall be governed by and construed in
accordance with the laws of the State of New York.

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         IN WITNESS WHEREOF, the undersigned has caused this Supplemental
Indenture to be duly executed as of the day and year first above written.

                                          Guarantor:

                                          Maine Logos, LLC,
                                          a Maine limited liability company

                                          By: Interstate Logos, L.L.C.
                                          Its: Managing Member

                                          By: Lamar Media Corp.
                                          Its: Managing Member

                                          By:  /s/ Keith A. Istre
                                             -----------------------------------
                                                Keith A. Istre
                                                Vice President - Finance and
                                                Chief Financial Officer
Attest:

By:      /s/ James R. McIlwain
   ------------------------------
     James R. McIlwain, Secretary

Accepted:

STATE STREET BANK AND TRUST
         COMPANY, as Trustee

By:      /s/ Andrew L. Sciorz
   ------------------------------
Title:   Assistant Vice President
   ------------------------------

                                       2<PAGE>
                                                                    EXHIBIT 10.1

                                JOINDER AGREEMENT

         JOINDER AGREEMENT dated as of August 30, 2001, by the undersigned,
Maine Logos, L.L.C., (the "Additional Subsidiary Guarantor"), in favor of The
Chase Manhattan Bank, as administrative agent for the Lenders party to the
Credit Agreement referred to below (in such capacity, together with its
successors in such capacity, the "Administrative Agent").

         Lamar Media Corp. (formerly Lamar Advertising Company), a Delaware
corporation (the "Borrower"), and certain of its subsidiaries (collectively, the
"Existing Subsidiary Guarantors" and, together with the Borrower, the "Securing
Parties") are parties to a Credit Agreement dated August 13, 1999 (as modified
and supplemented and in effect from time to time, the "Credit Agreement",
providing, subject to the terms and conditions thereof, for extensions of credit
(by means of loans and letters of credit) to be made by the lenders therein
(collectively, together with any entity that becomes a "Lender" party to the
Credit Agreement after the date hereof as provided therein, the "Lenders" and,
together with Administrative Agent and any successors or assigns of any of the
foregoing, the "Secured Parties") to the Borrower in an aggregate principal or
face amount not exceeding $1,000,000,000 (which, in the circumstances
contemplated by Section 2.01(d) thereof, may be increased to $1,400,000,000). In
addition, the Borrower may from time to time be obligated to one or more of the
Lenders under the Credit Agreement in respect of Hedging Agreements under and as
defined in the Credit Agreement (collectively, the "Hedging Agreements").

         In connection with the Credit Agreement, the Borrower, the Existing
Subsidiary Guarantors and the Administrative Agent are parties to the Pledge
Agreement dated September 15, 1999 (the "Pledge Agreement") pursuant to which
the Securing Parties have, inter alia, granted a security interest in the
Collateral (as defined in the Pledge Agreement) as collateral security for the
Secured Obligations (as so defined). Terms defined in the Pledge Agreement are
used herein as defined therein.

         To induce the Secured Parties to enter into the Credit Agreement, and
to extend credit thereunder and to extend credit to the Borrower under Hedging
Agreements, and for other good and valuable consideration the receipt and
sufficiency of which are hereby acknowledged, the Additional Subsidiary
Guarantor has agreed to become a party to the Credit Agreement and the Pledge
Agreement as a "Subsidiary Guarantor" thereunder, and to pledge and grant a
security interest in the Collateral (as defined in the Pledge Agreement).

         Accordingly, the parties hereto agree as follows:

         Section 1. Definitions. Terms defined in the Credit Agreement are used
herein as defined therein.

         Section 2. Joinder to Agreements. Effective upon the execution and
delivery hereof, the Additional Subsidiary Guarantor hereby agrees that it shall
become "Subsidiary Guarantor" under and for all purposes of the Credit Agreement
and the Pledge Agreement with all the rights and obligations of a Subsidiary
Guarantor thereunder. Without limiting the generality of the foregoing, the
Additional Subsidiary Guarantor hereby:

                  (i) jointly and severally with the other Subsidiary Guarantors
         party to the Credit Agreement guarantees to each Secured Party and
         their respective successors and assigns the

<PAGE>

         prompt payment in full when due (whether at stated maturity, by
         acceleration or otherwise) of all Guaranteed Obligations in the same
         manner and to the same extent as is provided in Article III of the
         Credit Agreement;

                  (ii) pledges and grants the security interests in all right,
         title and interest of the Additional Subsidiary Guarantor in all
         Collateral (as defined in the Pledge Agreement) now owned or hereafter
         acquired by the Additional Subsidiary Guarantor and whether now
         existing or hereafter coming into existence provided for by Article III
         of the Pledge Agreement as collateral security for the Secured
         Obligations and agrees that Annex 1 thereof shall be supplemented as
         provided in Appendix A hereto;

                  (iii) makes the representations and warranties set forth in
         Article IV of the Credit Agreement and in Article II of the Pledge
         Agreement, to the extent relating to the Additional Subsidiary
         Guarantor or to the Pledged Equity evidenced by the certificates, if
         any, identified in Appendix A hereto; and

                  (iv) submits to the jurisdiction of the courts, and waives
         jury trial, as provided in Sections 10.09 and 10.10 of the Credit
         Agreement.

         The Additional Subsidiary Guarantor hereby instructs its counsel to
deliver the opinions referred to in Section 6.10(a)(iii) of the Credit Agreement
to the Secured Parties.

                                       2

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         IN WITNESS WHEREOF, the Additional Subsidiary Guarantor has caused this
Joinder Agreement to be duly executed and delivered as of the day and year first
above written.

                                              Maine Logos, LLC,
                                              a Maine limited liability company

                                              By: Interstate Logos, L.L.C.
                                              Its: Managing Member

                                              By: Lamar Media Corp.
                                              Its: Managing Member

                                              By:  /s/ Keith A. Istre
                                                 -------------------------------
                                                    Keith A. Istre
                                                    Vice President - Finance and
                                                    Chief Financial Officer

Attested:

By:  /s/ James R. McIlwain
   ---------------------------------
     James R. McIlwain, Secretary

Accepted and agreed:

THE CHASE MANHATTAN BANK,
as Administrative Agent

By:      /s/ William E. Rottino
   ---------------------------------
Title:   Vice President

                                       3

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The undersigned hereby respectively pledges and grants a security interest in
the Pledged Equity and evidenced by the certificate listed in Appendix A hereto
and agrees that Annex 1 of the above-referenced Pledge Agreement is hereby
supplemented by adding thereto the information listed on Appendix A.

Interstate Logos, L.L.C., Issuee of the Membership Units of Maine Logos, L.L.C.

By: Lamar Media Corp.
Its: Managing Member

By:    /s/ Keith A. Istre
     -------------------------------
         Keith A. Istre
Title:   Vice President-Finance

                                       4

<PAGE>

SUPPLEMENT TO ANNEX 1

                                                 APPENDIX A TO JOINDER AGREEMENT

<Table>
<Caption>
PLEDGOR OWNERSHIP          ISSUER                    NO. SHARES      CERT. NO.      %
-----------------          ------                    ----------      ---------     ---
<S>                        <C>                       <C>            <C>            <C>
Interstate Logos, L.L.C.   Maine Logos, L.L.C.       1000 Units      2             100
</Table>

                                       5

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