Does a Missouri based contractor who did work in Iowa file a mechanics lien in my county or their county in Iowa?

I am a Contractor in Missouri. I did a commercial job in Iowa (I was a sub conractor). The Iowa contractor has not paid me. (over $40k still due) Do I file the mechanics lien in Iowa or Missouri? If in Iowa, must I do this in person at their county's court house? (Clarinda, Iowa) Thank you!