Early today, a gunman open fired at a baseball practice in Alexandria, Virginia. Donna Hoffman, an associate professor of political science at the University of Northern Iowa says while tragic, the event is not unique. "It’s important to remember in times like this that America often has violent events like this," she says. "There have only been 45 presidents in our nation’s history and four of them have been assassinated. There’s something about America in terms of our political culture perhaps