United States Securities and Exchange Commission Washington, D.C. 20549 Form 10-K (Mark One) ☒ Annual Report Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 For the year ended December 31, 2019 ☐ Transition Report Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 For the transition period from ______________ to ______________ Commission File Number 1-3548 ALLETE, Inc. (Exact name of registrant as specified in its charter) Minnesota 41-0418150 (State or other juris ...