 The municipality of Sumirago contains the "frazioni" (subdivisions, mainly villages and hamlets) Albusciago, Caidate, Menzago, and Quinzano.Sumirago is a centre of ancient origins, belonging since the very start to the city of Milano.In 1786, he started to be a part of the district of Varese, even if afterwards he returned to be a part of Milano's one.