This municipality having been created by virtue of republic act no. 4871 dated May 8, 1967, it classified as 4th class municipality. The municipality bounded as follows: Beginning from point 1, intersection of latitude 7⁰58′ and longitude 123⁰23′; thence due west until it intersects longitude 123⁰10′ called point 2; thence due north following partly the provincial boundary between Zamboanga del Norte and Zamboanga del Sur until it intersect latitude 8⁰06′ called point 3; thence due east until it intersect latitude 123⁰23′ called point 4; thence due south back to point 1; point of beginning.

     However, due to the creation of the municipality of Sominot by virtue of Batas Pambansa Bilang 60 dated March 27, 1980 the municipality of Midsalip is mother municipality of Sominot formerly Don Mariano Marcos, for this reason the area was reduced, and the shape of our map instead of rectangle as per technical description given during creation, became as what is reflected in the provincial map to this moment. There were boundaries conflict between neighboring municipalities and city, but the municipality of Midsalip and its officials adhere of what is legal and stated in the law of creating the municipality.

     Midsalip is an interior municipality located in the eastern part of the province of Zamboanga del Sur. It is 46 kilometer away from the capital city of Pagadian.  From the national highway, it is 21.8 kilometers inland. The municipality is bounded on the north by the municipality of Dumingag, and on the south by the city of Pagadian and municipality of Labangan, on the east by the municipality of Sominot and on the west by the province of Zamboanga del Norte.  It is situated approximately between latitude 8°00’43” to 8°01’42” north, and longitude 123°10’04” to 123°10’09” east.