 With the introduction of Interstate 65 in the mid 1970s, Millbrook's growth led to formal incorporation as a city in 1977.Once again, those seeking a more relaxing lifestyle discovered the interstate exits immediately north of the state capital and the Millbrook population grew even more.As of the census of 2010, there were 14,640 people, 5,446 households, and 4,069 families residing in the city.