Larslan is an unincorporated community in Valley County, Montana, United States. Larslan is 20 miles northeast of St. Marie. The community ha…Larslan is an unincorporated community in Valley County, Montana, United States. Larslan is 20 miles northeast of St. Marie. The community has a post office with ZIP code 59244. Next to the post office there is an old one-room school house, play structure and basketball court.