EXHIBIT 32.1

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 on Form 10-Q of Swift Transportation Company (the “Company”) for the quarter ending March 31, 2012, as filed with the Securities and Exchange Commission on the date hereof (the “Report”), we, the undersigned, certify, to the best of our knowledge, that:

(1) The Report fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 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.

SWIFT TRANSPORTATION COMPANY, a Delaware corporation
By:	/s/ Jerry Moyes
	Jerry Moyes
	Chief Executive Officer
May 8, 2012
By:	/s/ Virginia Henkels
	Virginia Henkels
	Executive Vice President and Chief Financial Officer
May 8, 2012