Final answer:
The Armory Show of 1913 was historically significant for American art as it introduced new artistic styles to the American public and inspired American artists to experiment and create their own artistic language.
Step-by-step explanation:
The Armory Show of 1913 was historically significant and served as a 'game changer' for the course of American art. It introduced the American public to the artistic styles of Impressionism, Fauvism, and Cubism, which were previously unfamiliar in the United States. By showcasing avant-garde European art alongside American works, the exhibition challenged traditional notions of art and inspired American artists to embrace experimentation and develop their own distinct artistic language.