Sumpor families are Croats and they are mostly from Donja Stubica area. In the past century, relatively most of Croatian residents bearing this family name were born in Donja Stubica area and in Zagreb.
Prevalence
About 80 people with faimily name Sumpor live in Croatia today, in 30 households. There were 50 of them in the middle of the past century, and their number increased by 50 percent. They are only located in four Croatian cities and 10 other places, mostly in Sesvete (30), Karivaros in Donja Stubica area (20), Dugo Selo (<10), Kutina (<10), and in Zagreb (<5).
In the sources analysed in the project Acta Croatica so far, the name is mentioned few times, the first time 2007 in source Encyclopaedia of Croatian Surnames.