The US Postal Service was founded.
Benjamin Franklin was named the first Postmaster General.
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President Harry Truman signed the National Security Act.
Niger President Mohamed Bazoum was removed from office by a military coup.
Albert Einstein's theory of gravitational redshift was proven after a telescope in Chile observed a black hole.
The Summer Olympic Games opening ceremony was held outdoors for the first time ever.
Italian adventurer and author Giacomo Casanova was arrested in Venice for his offensive remarks on religion.
