Hundreds of millions of Chinese are now traveling home to celebrate the Lunar New Year. It's the largest human migration on earth -- and it stretches the country's transportation system to the limit.
Passengers on a train from Guangzhou to Changchun. China's government estimates that 3.4 billion trips will be taken during the 40-day holiday travel period.
By Charles Riley @CRrileyCNN - Last updated February 07 2013 08:30 PM ET
