Murphy USA (MUSA) 10-Q 2018 Q1 Quarterly report

EXHIBIT32.1

CERTIFICATION PURSUANT TO

18 U.S.C. SECTION 1350,

AS ADOPTED PURSUANT TO

SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

In connection with the Quarterly Report of MurphyUSAInc.(the “Company”) on Form 10-Q for the period ended March 31, 2018 as filed with the Securities and Exchange Commission on the date hereof (the “Report”),I,  R.Andrew Clyde,  Principal Executive Officer of the Company, certify, pursuant toRule 13a-14(b) under the Securities Exchange Act of 1934 and18 U.S.C. § 1350, as adopted pursuant to § 906 of the Sarbanes-Oxley Act of 2002, thatto myknowledge:

(1) The Report fully complies with the requirements of section 13(a) or 15(d) of the Securities Exchange Actof 1934; and

(2) The information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Company.

Date: May 3, 2018

/s/ R. Andrew Clyde

R.Andrew Clyde

Principal ExecutiveOfficer

Ex. 32.1