Exhibit 99.1 PACKAGING CORPORATION OF AMERICA REPORTS SECOND QUARTER 2024 RESULTS Lake Forest, IL, July 23, 2024 – Packaging Corporation of America (NYSE: PKG) today reported second quarter 2024 net income of $199 million, or$2.21 per share, and net income of $199 million, or$2.20 per share, excluding special items. Second quarter net sales were $2.1 billion in 2024 and$2.0 billion in 2023. Diluted earnings per share attributable to Packaging Corporation of America shareholders Three Months Ended June 30 ...