Players hailing from more than 45 different countries will compete at the U.S. Open this year. American Serena Williams has the top seed for the women, with Simona Halep of Romania and Czech Petra Kvitova taking the second and third slot. For the men, Novak Djokovic takes the first seed for Serbia, while Switzerland rounds out the top three with Roger Federer and Stan Wawrinka, respectively. But which country has made its mark with the most wins since 1968? Find out below if your country gets the win.