In Croatia, Jerko families are Croats (from Dugo Selo area ). In the past century, relatively most of Croatian residents bearing this family name were born in Zagreb and in Dugo Selo area. In Prevlaka in Dugo Selo area every sixth inhabitant had the family name Jerko.
Prevalence
About 30 people with faimily name Jerko live in Croatia today, in 10 households. There were 30 of them in the middle of the past century, and their number remains constant. They are located in only five naselja i to in Dugo Selo (20), Oborovo in Dugo Selo area (<5), Zagreb (<5), Strmec in Samobor area (<5), and in Ivanic-Grad (<5).
Outside Croatia
Family name Jerko (including: Yerko , Ierko and Jerco ) is present in 11 countries on three continents. The family name "Jerko " is used by small number of people in the United States. "Yerko " is used by few people in the United States.
In the sources analysed in the project Acta Croatica so far, the name is mentioned few times, the first time 1935 in source Faculty of Humanities University of Zagreb Alumni.