President Donald Trump and first lady Melania Trump have kicked off the Freedom 250 Grand Prix in Washington. They led a slow lap in the presidential limousine through the downtown course Sunday. Soon after, the president waved the green flag to start the race and drivers began whipping through city streets, including a stretch along Pennsylvania Avenue not too far from the White House. The open-wheel race has cars whizzing past Washington’s monuments at speeds approaching 200 mph. It's the latest of Trump’s celebrations this year to mark America’s 250th birthday.