Full coverage: 2017 Spring Festival

It's the busiest time of the year at the printing factory of Zhengzhou Railway Bureau in Henan province. Since the end of December, it's been in a race against time to prepare tickets for 75 train stations in central and western China for the upcoming Spring Festival. In this 200-square-meter room, more than 1.2 million tickets are printed every day. But it needs to churn out at least 40 million altogether to cope with the extra demand.

“Once we find any problems on the tickets, we will shred them in the special shredding machine in this room. We do it quickly, and never leave it til the next day. That’s to make sure no defective tickets get out of this room,” said Wang Min at Zhengzhou railway bureau.

The Chinese Spring Festival is known as the world's largest annual human migration. The demand for train tickets is always huge. Getting your hands on one isn't simple. The main battleground shifted to the Internet in 2012. And last year, even though tickets could be purchased 60 days in advance, it was still a real struggle to get one.

"Chunyun started a few days ago. Today, no one waits for a ticket overnight at the ticket windows. It's huge relief for us," said Wang Yu, a ticket seller at Zhengzhou railway station.

Today, most bookings are made on the railway companies' official websites or their mobile phone apps. This puts an end to the scenes of migrant workers queuing or camping in from of the ticketing halls of major stations around the country. Scalpers have also been largely forced out of business, as travelers are required to match their identification cards with each online purchase.