UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 or ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 Form 10-K (Mark One) ☒ ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31, 2020 For the transition period from to Commission File no. 1-07615 Kirby Corporation (Exact name of registrant as specified in its charter) Nevada 74-1884980 (State or other jurisdiction of incorpora ...