He was appointed the second Poet Laureate Consultant in Poetry to the Library of Congress in 1987 , and twice received the Pulitzer Prize for Poetry , in 1957 and again in 1989 .
He became the second Poet Laureate Consultant in Poetry to the Library of Congress in 1987 . He received the Pulitzer Prize for Poetry two times ; in 1957 and again in 1989 .