1 EXHIBIT 4.6 SUPPLEMENTAL INDENTURE OF GUARANTORS THIS SUPPLEMENTAL INDENTURE dated as of September 15, 1999 is delivered pursuant to Section 10.04 of the Indenture dated as of November 15, 1996 (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 are Guarantors under the Indenture with all of the rights and obligations of a Guarantor thereunder. 2. The undersigned hereby grant, ratify and confirm 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 represent and warrant that the representations and warranties set forth in the Indenture, to the extent relating to the undersigned as Guarantors, 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. 1 2 IN WITNESS WHEREOF, the undersigned have caused this Supplemental Indenture to be duly executed as of the day and year first above written. Guarantors: LAMAR MW SIGN CORPORATION LAMAR MARTIN CORPORATION LAMAR NEVADA SIGN CORPORATION LAMAR OUTDOOR CORPORATION LAMAR WHITECO OUTDOOR CORPORATION DOWLING COMPANY, INCORPORATED HARDIN DEVELOPMENT CORPORATION LINDSAY OUTDOOR ADVERTISING INC. PARSONS DEVELOPMENT COMPANY REVOLUTION OUTDOOR ADVERTISING, INC. SCENIC OUTDOOR MARKETING & CONSULTING, INC. WESTERN POSTER SERVICE, INC. By: /s/ Keith A. Istre ---------------------------------------- Keith A. Istre Vice President - Finance and Chief Financial Office LAMAR WEST, L.P. By: Lamar MW Sign Corporation, Its General Partner By: /s/ Keith A. Istre ---------------------------------------- Keith A. Istre Vice President - Finance and Chief Financial Officer 2 3 OUTDOOR PROMOTIONS WEST, LLC TRANSIT AMERICA LAS VEGAS, L.L.C. TRIUMPH OUTDOOR LOUISIANA, LLC TRIUMPH OUTDOOR RHODE ISLAND, LLC By: Triumph Outdoor Holdings, LLC, its manager By: Lamar Outdoor Corporation, its manager By: /s/ Keith A. Istre ---------------------------------------- Keith A. Istre Vice President - Finance and Chief Financial Officer TRIUMPH OUTDOOR HOLDINGS, LLC By: Lamar Outdoor Corporation, its manager 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 Sinasky -------------------------------------- Title: Assistant Vice President ----------------------------------- 3