BLACK HILLS CORP SD

IMPORTANT NOTICE REGARDING THE AVAILABILITY OF PROXY MATERIALS

FOR THE SHAREHOLDER MEETING TO BE HELD ON APRIL 23, 2024

Shareholders may view this proxy statement, our form of proxy and our 2023 Annual Report to Shareholders over the Internet by accessing our website atwww.blackhillscorp.com. Information on our website does not constitute a part of this proxy statement.

ANNUAL MEETING OF SHAREHOLDERS

Tuesday, April 23, 2024

9:30 a.m., Local Time

Horizon Point

Company’s Corporate Headquarters

Rapid City, SD 57702

Important Notice Regarding the Availability of Proxy Materials for the Annual Meeting:

The Notice and Proxy Statement and our 2023 Annual Report to Shareholders are available atwww.blackhillscorp.com.

This proxy is solicited by the Board for use at the Annual Meeting on April 23, 2024.

The undersigned hereby appoints Linden R. Evans, Brian G. Iverson and Kimberly F. Nooney, and each of them, with full power of substitution, to vote all shares of the undersigned at the Annual Meeting of Shareholders to be held at 9:30 a.m., local time, April 23, 2024, at Horizon Point, the Company’s corporate headquarters, 7001 Mount Rushmore Road, Rapid City, SD 57702, and at any adjournment thereof, upon all subjects that may properly come before the meeting, including the matters described in the Proxy Statement furnished herewith.

Your vote is important! Ensure that your shares are represented at the meeting.

Either (1) submit your proxy by touchtone telephone, (2) submit your proxy by Internet, or (3) mark, date, sign, and return this proxy in the envelope provided. If no directions are given, properly executed proxies will be voted in accordance with the Board's recommendation on all matters listed on this proxy, and at their discretion on any other matters that may properly come before the meeting.

See reverse for voting instructions.

COMPANY #

VOTE BY INTERNET, TELEPHONE OR MAIL

24 HOURS A DAY, 7 DAYS A WEEK

Your phone or Internet vote authorizes the named Proxies to vote your shares in the same manner as if you marked, signed and returned your proxy card.

VOTE BY INTERNET/MOBILE —www.proxypush.com/bkh

Use the Internet to vote your proxy until 11:59 p.m. (CT) on April 22, 2024.

VOTE BY PHONE— 1-866-883-3382

Use a touch-tone telephone to vote your proxy until 11:59 p.m. (CT) on April 22, 2024.

VOTE BY MAIL

Mark, sign and date your proxy card and return it in the postage-paid envelope provided.

If you vote your proxy by internet or by phone, you do NOT need to mail back your Proxy Card.

The Board Recommends a Vote FOR the Nominees in Item 1 and FOR Items 2 and 3.

(Instructions: To cumulate votes for any indicated nominee for election to the

nominee's class, write the number(s) of the nominee(s) and the number of shares

for such nominee in the box provided to the right.)

THIS PROXY, WHEN PROPERLY EXECUTED, WILL BE VOTED AS DIRECTED OR, IF NO DIRECTION IS GIVEN, WILL BE VOTEDFOR THE NOMINEES IN ITEM 1 ANDFOR ITEMS 2 AND 3.

Please sign exactly as your name(s) appear on Proxy. If held in joint tenancy, all persons should sign. Trustees, administrators, etc., should include title and authority. Corporations should provide full name of corporation and title of authorized officer signing the Proxy.