US Secret Service - the United States intelligence agency that protects current and former presidents and vice presidents and their immediate families and protects distinguished foreign visitors; detects and apprehends counterfeiters; suppresses forgery of government securities and documents.
It's  blessings not blessing.. The entire clause is ...to secure the  blessings of liberty to ourselves and our posterity....    The blessings of liberty refers to all of the benefits that are  afforded by having liberty.
Best Answer: posterity: Definition: 1. generations to come in the future; 2. all of a person's descendants. Synonyms: offspring, future generations, descendants, progeny. Antonyms: ancestors. Tips: Posterity is a more sophisticated way of referring to future generations and the idea of saving or documenting knowledge for use in the future. Usage Examples: