The world's largest annual migration is underway as hundreds of millions of Chinese people head back home to celebrate the Lunar New Year with their families. The week-long holiday is surrounded by a 40-day travel frenzy known as "Chunyun", during which the total volume of passengers this year is expected to be almost three billion. That's about two journeys for every single member of China's population.

Bus terminals, train stations and airports will be pushed to their limits as they try to cope with the massive increase in passengers. Delays can lead to meltdowns. In 2016, around 100,000 people were left waiting at Guangzhou Railway Station overnight after train services were cancelled due to heavy snow. In this gallery, we present Spring Festival travel scenes from the last few years to give an idea of what passengers may face this year.

China New Year travel
2 February 2016: Thousands of passengers are kept in a holding area (and an overflow area) outside Guangzhou railway station after snow and ice disrupted the world's largest annual human migration AFP
China New Year travel
2 February 2016: An overhead view of tens of thousands of people waiting to enter Guangzhou Railway Station because of weather delays Lin Hongxian/Southern Metropolis Daily/Reuters
China New Year travel
1 February 2016: Passengers crowd into the station waiting hall after trains were delayed due to heavy snow, in Guangzhou, Zhejiang province, on 1 February 2016 Reuters
China New Year travel
A couple share a duvet at midnight at a railway station in Guangzhou, Guangdong province, on 25 January 2016 Reuters
China New Year travel
Endlessly snaking lines of passengers fill the waiting hall at Hankou Railway Station in Wuhan, Hubei province, on 15 January 2012 Reuters
China New Year travel
Passengers rush to board trains at Changsha Railway Station in Hunan province on 8 January 2012 Reuters
China New Year travel
Passengers board a train through its windows at a railway station in Wuxi, Jiangsu province on 10 January 2009 Reuters
China New Year travel
Passengers and their belongings are pictured through a window of a packed train carriage in Hefei, Anhui province, on 4 February 2013 Reuters
China New Year travel
Passengers are seen crammed inside a train carriage in Lanzhou, Gansu province on 21 January 2009 Reuters
China New Year travel
A passenger throws a piece of rubbish on the floor as a cleaner collects refuse on a carriage of a train travelling from Shenzhen to Zhengzhou on 22 January 2014
China New Year travel
Passengers are seen in a crowded carriage on a train travelling from Ningbo in Zhejiang province to Chengdu, capital of the southwest Sichuan province, on 18 January 2014 Reuters
China New Year travel
Men hang onto their bulky luggage as they wait to enter a railway station in Beijing on 17 February 2015 Kevin Frayer/Getty Images
China New Year travel
28 January 2013: Parents take care of their two children in the square outside Guangzhou train station Bai Shi/AFP
China New Year travel
Huge crowds of passengers wait to get into Zhengzhou Railway Station in Henan province on 1 October 2014 Reuters
China New Year travel
China New Year travel
5 February 2010: A father sees his seven-year-old son off at a railway station in Hefei, Anhui province. The child was travelling back with his mother to their hometown in Qinghai province while the father stayed behind to run a restaurant Reuters

Lunar New Year, also known as the Spring Festival, is the most important holiday in China. Many people work in big cities hundreds of miles from their home towns, and the week-long national holiday is the only time in the year that they can see their families.

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