The main purpose of this legislation is to require the United States Postal Service to create a single, unique ZIP Code specifically for Highland City, Utah. This change aims to improve mail delivery efficiency and clarity for residents and businesses in the area. The key provision of this legislation mandates that the Postal Service must designate this unique ZIP Code within 270 days after the law is enacted. This means that once the law is passed, the Postal Service has a set timeframe to implement the change.