On this day: July 1

POSTED: 1:06 PM PDT June 28, 2013    UPDATED: 11:00 PM PDT June 30, 2013 
Sony Walkman cassette player

The Battle of Gettysburg begins, America's first zoo opens, the first Tour de France starts, the Sony Walkman hits the market, the PG-13 movie rating is introduced, and the Deepwater Horizon oil spill breaks an unfortunate record, all on this day.