Final answer:
The author of "Spoon River Anthology", a masterpiece that made him an important American poet, is Edgar Lee Masters. This work provides a series of free verse epitaphs that paint a picture of life in a small American town.
Step-by-step explanation:
The author whose masterpiece "Spoon River Anthology" established him as an important American poet is Edgar Lee Masters. This collection consists of short, free verse poems that collectively narrate the epitaphs of the deceased residents of Spoon River, a fictional small town. Published in 1915, "Spoon River Anthology" was a significant departure from the traditional poetic style of the time and offered a unique and candid view of small-town American life.
In contrast to Masters, Robert Frost was known for his depiction of rural New England life, earning him four Pulitzer Prizes. While Langston Hughes was a central figure of the Harlem Renaissance, using his poetry to express the urban African American experience. However, neither Frost nor Hughes wrote the "Spoon River Anthology".
The work of Edgar Lee Masters in the "Spoon River Anthology" remains an influential piece of American literature and reflects a significant literary achievement that continues to be studied and admired.