In the year of 1865, a large municipal reform occurred in which the municipality, named Simo, received its actual limits, even though the area had long been referred to as Simoksi and the residents simolaisiksi.
Vuonna 1865 suuressa kuntauudistuksessa Simon kunta sai varsinaiset rajansa, vaikka aluetta oli jo kauan kutsuttu Simoksi ja asukkaita simolaisiksi.