Today in History Today is Monday, July 5, the 186th day of 2021. There are 179 days left in the year. Today’s Highlight in History: On July 5, 1971, President Richard Nixon certified the 26th Amendment to the U.S. Constitution, which lowered the minimum voting age from 21 to 18. On this date: In 1687, Isaac Newton first published his Principia Mathematica, a three-volume work setting out his mathematical principles of natural philosophy. In 1811, Venezuela became the first South American country to declare independence from Spain. In 1935, President Franklin D. Roosevelt signed the National Labor Relations Act. In 1943, the Battle of Kursk began during World War II; in the weeks that followed, the Soviets were able to repeatedly repel the Germans, who eventually withdrew in defeat.