EXHIBIT 4.2

                                CSX CORPORATION

                                      AND

                           THE CHASE MANHATTAN BANK,
                                    TRUSTEE

                        _______________________________

                              THIRD SUPPLEMENTAL
                                   INDENTURE

                          DATED AS OF APRIL 22, 1998
                        _______________________________


                               SENIOR SECURITIES

          THIRD SUPPLEMENTAL INDENTURE, dated as of April 22, 1998 between CSX
Corporation, a Virginia corporation (the "Company"), and The Chase Manhattan
Bank, a New York banking corporation, Trustee (the "Trustee").


                            RECITALS OF THE COMPANY

          WHEREAS, the Company has heretofore executed and delivered to the
Trustee a certain indenture, dated as of August 1, 1990 and supplemented by the
First Supplemental Indenture dated as of June 15, 1991 and the Second
Supplemental Indenture dated as of May 6, 1997 (the "Second Supplemental
Indenture") (the indenture, as so supplemented, is herein called the
"Indenture"), pursuant to which one or more series of unsecured debentures,
securities or other evidences of indebtedness of the Company (herein called the
"Securities") may be issued from time to time;

          WHEREAS, Section 901 of the Indenture provides that the Company, when
authorized by a Board Resolution, and the Trustee may at any time and from time
to time enter into one or more indentures supplemental to the Indenture for the
purpose, among other things, of (i) changing or eliminating any of the
provisions of the Indenture, provided that such change or elimination shall
become effective only when there is no Security Outstanding of any series
created prior to the execution of such supplemental indenture which is entitled
to the benefit of such provision, (ii) establishing the form or terms of
Securities of any series and any related coupons as permitted by Sections 201
and 301 of the Indenture or (iii) making any other provisions with respect to
matters or questions arising under the Indenture, provided that such action
shall not adversely affect the interests of the Holders of Securities of any
series or any related coupons in any material respect;

 
                                       2
                                           
          WHEREAS, the Second Supplemental Indenture amended and supplemented
the terms of the Indenture with respect to the May 1997 Securities (as defined
in the Second Supplemental Indenture);

          WHEREAS, the Second Supplemental Indenture, by its terms, was
applicable only to the May 1997 Securities;

          WHEREAS, the Company, pursuant to the foregoing authority, proposes in
and by this Third Supplemental Indenture to amend the Indenture with respect to
all series of Securities issued under the Indenture on or after May 6, 1997 by
making the terms, provisions and conditions of the Second Supplemental Indenture
applicable to all such series of Securities; and

          WHEREAS, all things necessary to make this Third Supplemental
Indenture a valid agreement of the Company and the Trustee and a valid amendment
of and supplement to the Indenture have been done.

          NOW, THEREFORE, THIS THIRD SUPPLEMENTAL INDENTURE WITNESSETH:

          For and in consideration of the premises and the purchase of the
Securities by the Holders thereof, it is mutually covenanted and agreed, for the
equal and proportionate benefit of all Holders of any series of Securities
issued on or after May 6, 1997, as follows:


                                  ARTICLE ONE

          The terms, provisions and conditions of the Second Supplemental
Indenture (except to the extent such terms, provisions or conditions would limit
the applicability of the Second Supplemental Indenture to the May 1997
Securities) shall apply to all series of Securities issued under the Indenture
on or after May 6, 1997.


                                  ARTICLE TWO

          Section 2.1  Incorporation of Indenture.  All the provisions of this
                       --------------------------                             
Third Supplemental Indenture shall be deemed to be incorporated in, and made a
part of, the Indenture; and the Indenture, as supplemented by this Third
Supplemental Indenture, shall be read, taken and construed as one and the same
instrument and shall be binding upon all the Holders of Securities.

          Section 2.2  Counterparts.  This Third Supplemental Indenture may be
                       ------------                                           
executed in any number of counterparts, each of which so executed shall be
deemed to be an original, but all such counterparts shall together constitute
but one and the same instrument.

 
                                       3

          Section 2.3  Successors and Assigns.  All covenants and agreements in
                       ----------------------                                  
this Third Supplemental Indenture by the Company and the Trustee shall bind
their respective successors and assigns, whether so expressed or not.

          Section 2.4  Separability Clause.  In case any provision in this Third
                       -------------------                                      
Supplemental Indenture shall be invalid, illegal or unenforceable, the validity,
legality and enforceability of the remaining provisions shall not in any way be
affected or impaired thereby.

          Section 2.5  Benefits of Third Supplemental Indenture.  Nothing in
                       ----------------------------------------             
this Third Supplemental Indenture, express or implied, shall give any person,
other than the parties hereto and their successors hereunder and the Holders of
Securities issued on or after May 6, 1997, any benefit or any legal or equitable
right, remedy or claim under this Third Supplemental Indenture.  Except as
expressly supplemented or amended as set forth in this Third Supplemental
Indenture, the Indenture is hereby ratified and confirmed, and all the terms,
provisions and conditions thereof shall be and continue in full force and
effect.  The Trustee accepts the trusts created by the Indenture, as amended and
supplemented by this Third Supplemental Indenture, and agrees to perform the
same upon the terms and conditions in the Indenture as amended and supplemented
by this Third Supplemental Indenture.

          Section 2.6. Defined Terms.  All terms used in this Third
                       -------------                               
Supplemental Indenture which are defined in the Indenture and not otherwise
defined herein shall have the meanings assigned to them in the Indenture.

 
          IN WITNESS WHEREOF, the parties hereto have caused this Third
Supplemental Indenture to be duly executed, and their respective corporate seals
to be hereunto affixed and attested, all as of the day and year first above
written.


                                     CSX CORPORATION
                                     
                                     
                                     
[Seal]                               By: /s/ David D. Owen                      
                                        ---------------------------------------
                                     Name:  David D. Owen
                                     Title: Managing Director--Corporate Finance


Attest:  /s/ Rachel E. Geiersbach             
       ----------------------------------------
     Assistant Corporate Secretary



[Seal]                               THE CHASE MANHATTAN BANK, as Trustee
                             
                             
                             
                                     By: /s/ Ronald J. Halleran                
                                        ----------------------------------------
                                     Name:  Ronald J. Halleran
                                     Title: Second Vice President


Attest: /s/ [Signature]                       
       ----------------------------------------
     Title: Assistant Secretary


THIRD SUPPLEMENTAL INDENTURE

 
State of Virginia
City of Richmond    ss.:

          On the 22nd day of April, 1998, before me personally came David D.
Owen to me known, who, being by me duly sworn, did depose and say that he is
Managing Director--Corporate Finance of CSX Corporation, one of the corporations
described in and which executed the foregoing instrument; that he knows the seal
of said corporation; that the seal affixed to said instrument is such corporate
seal; that it was so affixed by authority of the Board of Directors of said
corporation, and that he signed his name thereto by like authority.

(Notarial Seal)  /s/ Cynthia H. Freeze
                 -----------------------

THIRD SUPPLEMENTAL INDENTURE

 
State of New York
County of           ss.:

          On the 22nd day of April, 1998, before me personally came Ronald J.
Halleran to me known, who, being by me duly sworn, did depose and say that he is
a Second Vice President of The Chase Manhattan Bank, one of the corporations
described in and which executed the foregoing instrument; that he knows the seal
of said corporation; that the seal affixed to said instrument is such corporate
seal; that it was so affixed by authority of the By-Laws of said corporation,
and that he signed his name thereto by like authority.

(Notarial Seal)  /s/ Emily Fayan
                 ------------------------

THIRD SUPPLEMENTAL INDENTURE