Erdelja families are Croats and they are mostly from Krapina area. In the past century, relatively most of Croatian residents bearing this family name were born in Krapina area and in Zagreb.
Prevalence
About 200 people with faimily name Erdelja live in Croatia today, in 80 households. There were 160 of them in the middle of the past century, and their number increased by 30 percent. They are located in the most of Croatian counties, in 15 cities and 21 other places, mostly in Zagreb (60), Mihovljan in Krapina area (40), Karlovac (20), Varazdin (15), and in Gornja Semnica in Krapina area (10).
Outside Croatia
Family name Erdelja is present in three countries.
In the sources analysed in the project Acta Croatica so far, the name is mentioned few times, the first time 1902 in source Hartmann's General List of Apartments in Zagreb.