What does it mean when a governed area takes an adjacent ungoverned area into its boundaries

The court ruled that a general grant of one-mile extraterritorial jurisdiction in the city's as of 1927. As the post–World War II development boom took off, a good deal of the land was taken over. Authority decided to adopt zoning ordinances in the one-mile area surrounding the city. Boundaries typically follow property lines but are not required to do so.