He was born in Chiavari, and while his father wished him to join the merchant marine, by 1845 he had decided to study painting, and participated in his first exhibition in Genoa.
For a 1913 exhibition, the painter and art critic Sartorio spoke of Raggio as a man of simple nature, a believer, who does not know what the world owes to the value of his genius... bypassed and excluded between two generations of painters... (he is an) Artist not to budging an inch from the convictions which he had set himself, and his paintings, from a young age to today, have only one character, a single focus: to tell the story of the humble inhabitants of the Roman Campagna in communion with the herds of sheep and cows.
He depicts views of the town devastated by floods and cataclysms, desolate with fever, and in which living descendants of those aborigines, who conserve the seeds of Ancient Rome, and of the right of Catholic morality.
The population while poor and stray, maintains the innate goodness, spirituality, generous and fantastic, and fair in his humility, this has pleased the Ligurian painter.
Due to his advanced state of poverty, a commission from the Società Economica di Chiavari, composed of Pietro Gaudenzi, Giuseppe Canevelli, and Luigi Brizzolara, approached him to buy some of his works at a reasonable price.