The calculated distance (air line) between Selm and Oer-Erkenschwick is approximately 10 miles respectively 15 kilometers.
By car or train, the actual journey to Oer-Erkenschwick is certainly longer, as only the direct route (as the crow flies) between Selm and Oer-Erkenschwick has been calculated here.
Air line (approximately)
15 kilometers
8 nautical miles