Exhibit 16 Office of the Chief Accountant Securities and Exchange Commission 450 Fifth Street, N.W. Washington, D.C. 20549 May 3, 2002 Dear Sir or Madam: We have read the four paragraphs of Item 4 included in the Form 8-K of Knight Transportation, Inc., dated April 29, 2002, (Commission File Number: 000-24946) filed with the Securities and Exchange Commission and are in agreement with the statements contained therein. Very truly yours, /s/ Arthur Andersen LLP tlw Copy to: Timothy M. Kohl Chief Financial Officer, Knight Transportation, Inc.