MICHAEL J. PETRO
LIMITED POWER OF ATTORNEY FOR
SECTION 16 REPORTING OBLIGATIONS

     Know all by these presents, that the undersigned hereby
makes, constitutes and appoints Roselyn R. Bar as the
undersigned's true and lawful attorney-in-fact, with full
power and authority as hereinafter described on behalf of and
in the name, place and stead of the undersigned to:

     (1)  prepare, execute, acknowledge, deliver and file
Forms 3, 4, and 5 (including any amendments thereto and
including any Forms 144) with respect to the securities of
Martin Marietta Materials, Inc. a North Carolina corporation
(the "Company"), with the United States Securities and
Exchange Commission, any national securities exchanges and the
Company, as considered necessary or advisable under
Section 16(a) of the Securities Exchange Act of 1934 and the
rules and regulations promulgated thereunder, as amended from
time to time (the "Exchange Act");

     (2)  seek or obtain, as the undersigned's representative
and on the undersigned's behalf, information on transactions
in the Company's securities from any third party, including
brokers, employee benefit plan administrators and trustees,
and the undersigned hereby authorizes any such person to
release any such information to the undersigned and approves
and ratifies any such release of information; and

     (3)  perform any and all other acts which in the
discretion of such attorney-in-fact are necessary or desirable
for and on behalf of the undersigned in connection with the
foregoing.

The undersigned acknowledges that:

     (1)  this Power of Attorney authorizes, but does not
require, such attorney-in-fact to act in her discretion
on information provided to such attorney-in-fact without
independent verification of such information;

     (2)  any documents prepared and/or executed by
such attorney-in-fact on behalf of the undersigned pursuant to
this Power of Attorney will be in such form and will contain
such information and disclosure as such attorney-in-fact, in
her discretion, deems necessary or desirable;

     (3)  neither the Company nor such attorney-in-
fact assumes (i) any liability for the undersigned's
responsibility to comply with the requirement of the Exchange
Act, (ii) any liability of the undersigned for any failure to
comply with such requirements, or (iii) any obligation or
liability of the undersigned for profit disgorgement under
Section 16(b) of the Exchange Act; and

     (4)  this Power of Attorney does not relieve the
undersigned from responsibility for compliance with the
undersigned's obligations under the Exchange Act, including
without limitation the reporting requirements under Section 16
of the Exchange Act.

     The  undersigned hereby gives and grants the
foregoing attorney-in-fact full power and authority to do and
perform all and every act and thing whatsoever requisite,
necessary or appropriate to be done in and about the foregoing
matters as fully to all intents and purposes as the
undersigned might or could do if present, hereby ratifying all
that each such attorney-in-fact of, for and on behalf of the
undersigned, shall lawfully do or cause to be done by virtue
of this Limited Power of Attorney.

     This Power of Attorney shall remain in full force and
effect until revoked by the undersigned in a signed writing
delivered to such attorney-in-fact.

     IN WITNESS WHEREOF, the undersigned has caused this Power
of Attorney to be executed as of this 2nd day of August, 2021.


                         _/s/_Michael_J._Petro_______
                         Michael J. Petro