Expansion of the museum was again required to suitably display a collection that now included nearly every artistic medium. The bold solution was to build over the Illinois Central Railroad tracks that bordered the Art Institute’s east wall.
Additions for both the school and museum were added and included memorials to two young men who died in World War I: the George Alexander McKinlock Jr. Memorial Court (in 1924) and the Kenneth Sawyer Goodman Theater (in 1925). The Art Institute's holdings of Impressionist and Post-Impressionist paintings were immeasurably enhanced by the bequest of 52 paintings from Bertha Honoré Palmer in 1924 and the 1925 gift of the Helen Birch Bartlett Memorial Collection, which contained the famous Sunday Afternoon on La Grande Jatte—1884, (1884-86). In the depths of the Great Depression, the museum received the single most comprehensive gift of art in its history, the bequest of Martin A. Ryerson. This donation contained masterpieces ranging from American and European paintings dating to the 15th century to textiles, prints and drawings, Asian art, and European decorative arts.