When was Saint Augustine of Hippo canonized?

St. Augustine was declared a saint before the official canonization process was instituted in the 12th century. He would have been declared a saint to the bishop by those who knew him best and were familiar with his life and merits. The local bishop would them make the decision. Today only the pope can declare saints after years of study by the Sacred Congregation for the Causes of Saints in the Vatican. The church does not create saints. Only God can do that. The Church "screens" candidates for sainthood to determine if they had a life worthy of emmulation. In other Words, do they make good role models. Also, the Church has to be assured that the person is actually in Heaven. That is the reason that today a number of miracles must be verified before a person can be declared a saint.