What is associated with: approved in the 1950s this compound has been added to the drinking water of about half of the us population?

What is referred to by 'approve an amendment 6'? What is associated with: approved august 27 1789 this french document proclaimed that men are born remain free? What is associated with: approved in 1939 the seal of this city in new york state features a barge being towed through… What is associated with: approved in 1977 projected for launch in 1983 the hst didnt get airborne until this year in wh… What is associated with: approximately 1094 yards? Based on the clue 'approximately 2 million k 12 public school teacher...', what is the answer? Based on the clue 'approximately 60 miles northwest of mount mckinley', what is the answer? Based on the clue 'approximately 7 out of every 10 people over 75 are...', what is the answer?