Final answer:
Langston Hughes is the national poet known for writing in dialect, significant for his role in the Harlem Renaissance and expressive of the African American experience and cultural identity.
Step-by-step explanation:
The national poet who is well-known for often writing in dialect is Langston Hughes. Hughes was a central figure of the Harlem Renaissance, an epoch during which African American artists, writers, and musicians sought to reinvigorate African American culture and aesthetics. His poetry frequently reflected the voices and experiences of African Americans, using the vernacular of the time to express themes of marginalization and cultural identity. Poems like "The Negro Speaks of Rivers" (1921) helped solidify his standing as a significant American poet. In contrast, Robert Frost, although a highly celebrated American poet, was not particularly known for writing in dialect. Frost's poetry, such as the famous recitation of "The Gift Outright" at John F. Kennedy's inauguration, employed American vernacular in a traditional poetic form, reflecting the duality of a changing America.