Mill Plain is an unincorporated area in the City of Danbury, Connecticut, United States.

[1] It is located in the westernmost part of the city, bordering the town of Southeast, New York.

Defined as a village in the western part of Danbury,[2] Mill Plain has also historically been considered a semi-autonomous hamlet.

Five years later, Senior built a hat manufacturing shop in the area, which operated until 1892.

[8] Mill Plain station, was built in 1881, and closed in 1928 after being acquired by the New York, New Haven and Hartford Railroad.