It's been a wild start to the Labor Day holiday in China. Tickets at Hongqiao Railway Station, one of China's largest railway stations, were sold out nationwide on day one. And for the first time ever, all tickets to Beijing's Summer Palace from April 29 to May 1 sold out online. Metros in most cities across the country have extended service hours into the wee hours of the morning or are operating continuously overnight. But how many people actually travel in China during the Labor Day holiday?