Simplify the following text for a Grade 10 native English-speaking person.
Original: The Postal Reorganization Act signed by President Richard Nixon on August 12 , 1970 , replaced the cabinet-level Post Office Department with the independent United States Postal Service .
Simplified: The Postal Reorganization Act was signed by President Richard Nixon on August 12 , 1970 . It replaced the cabinet-level Post Office Department with the independent Postal Service on July 1 , 1971 .