Event:
9th Postmaster General: John McLean of Ohio takes office
More Notable Events on July 1:
1997 U.K. returns Hong Kong to China
1963 U.S. postal service institutes zip code system, Zone Improvement Plan
1917 257cm-mirror for Mount Wilson Observatory mounted
1916 Coca-Cola brings current coke formula to the market
1907 World's 1st air force established in the U.S. Army
