The district was created in 1883, then named
Sanam Chaeng. When the district office was moved to
Ban Huai Kaeo, the district name was changed to
Huai Kaeo as well. When in 1898 the Thai government built the Northern Railway through the district, the district center was moved to
Ban Sao (Thai บ้านเซ่า) and the district name was changed back to
Sanam Chaeng. In 1917 it was renamed
Ban Sao as the name of the tambon of the district center. Finally the Thai government changed the name to
Ban Mi in 1939. The name
Ban Mi is the name of an old town of
Phuan people who migrated from
Laos to
Siam around 1870. The name originates from a hand weaving method to weave cotton or silk fabric, named
Mat Mi (มัดหมี่) in Thai. ==Geography==