Which composer is cited for using nationalist elements in their music from the United States?

Gershwin is recognized for incorporating distinctly American elements in his compositions, blending classical music with jazz and popular music influences. His works, such as "Rhapsody in Blue" and "Porgy and Bess," reflect a unique fusion of cultures and styles, showcasing the vibrancy and diversity of American music. This ability to merge these distinct musical influences embodies the essence of American nationalism in music, as Gershwin drew inspiration from the sounds and rhythms of American life, ultimately creating a sound that resonates with the American identity.

In contrast, while Holst and Vaughan Williams are important composers, they primarily focused on English folk traditions rather than American nationalist music. Kodály, known for his emphasis on Hungarian folk music, also does not fit into the American context. Therefore, Gershwin stands out as the composer who effectively integrated elements representing the United States into his music.