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On this day: August 20

POSTED: 12:46 AM Aug 19 2012   UPDATED: 11:00 PM Aug 19 2013

Charles Darwin publishes his theory of evolution, the NFL is founded, Lou Gehrig belts his 23rd career grand slam and NASA heads for Mars, all on this day.

OTD August 20 - Presidio Tucson
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Tucson Presidio Trust for Historic Preservation

1775: The Spanish establish the Presidio San Augustin del Tucson in the town that will become Tucson, Ariz.