Exhibit 23.1

KPMG LLP

Aon Center

Suite 5500

200 E. Randolph Street

Chicago, IL 60601-6436

Consent of Independent Registered Public Accounting Firm

We consent to the use of our report dated February 27, 2025, with respect to the consolidated financial statements of Packaging Corporation of America, and the effectiveness of internal control over financial reporting, incorporated herein by reference, and to the reference to our firm under the heading “Experts” in the prospectus.

Chicago, Illinois

August 11, 2025

KPMG LLP, a Delaware limited liability partnership and a member firm of

the KPMG global organization of independent member firms affiliated with

KPMG International Limited, a private English company limited by guarantee.