Southbury [New Haven County] was named in May, 1731 as the south part of Woodbury. It was incorporated from Woodbury in May 1787. Total area, 40.0 sq. miles, Land area, 39.1 sq. miles. Population, est., 18,471. Voting districts, 5. Principal industries, IBM and Com-Sat tracking station. Location of Southbury Training School.Southbury includes the area known as South Britain.