Alegrete was settled in 1816 and became a municipality in 1857. It is the hometown of the abolitionist leader Franklin Gomes Souto, of the politician, diplomat and statesman Osvaldo Aranha, first President of the United Nations General Assembly, and of the Brazilian poet Mário Quintana. Every September 20 (Ragamuffin War Day), about 8,000 young, adult and old horsemen and horsewomen parade through its streets, using their native costumes and riding their horses with trappings.