The big data map of migration published by Baidu shows the busiest routes on the first day of the Spring Festival travel rush.

Big data on travel patterns shows that while many people are leaving metropolises for family reunions during the Spring Festival travel rush this year, some will be traveling in the reverse direction for the same reason.

The data published by search engine Baidu shows that on Jan 24, the first day of this year's Spring Festival travel rush, Beijing and Shanghai are the busiest cities with the combined outbound traffic taking up 40 percent of the whole amount.

Besides, Beijing is the city with most people arriving on the first day of the travel rush and Shanghai comes third. In previous years, metropolises like Beijing tend to become "empty cities" during the Spring Festival holidays as a great many migrant workers and students leave for their hometown.

According to a staff member from Baidu, the influx of people to big cities is probably due to the fact that many young people have settled in these cities and chose to let their parents come to big cities to join them for the Spring Festival.

Passengers walk to board an extra train bound to Anqing city, East China's Anhui province, at Beijing West Railway Station on Jan 24, 2016. The train marks the start of travel rush of the 40-day Spring Festival travel. [Photo/Chinanews.com]

Data published by China Railway Corp, the country's railway operator, shows that in the seven-day period prior to the New Year's Eve, Guangzhou tops the list of cities with most outbound passengers – 2.39 million passengers will leave the city during this period – followed by Beijing and Shanghai. This is the first time that the CRC published such big data.

Wuhan, a traffic hub in Central China, takes the first place on the list of passenger arrival volume, with around 1 million people expected to get to the city in the run-up to the Spring Festival, followed by Guangzhou and Beijing.

In terms of traffic along the routes, Beijing to Shanghai is the busiest of all routes. Other busy routes include train journeys from Beijing, Shanghai and Guangzhou to places in central and western China, where a lot of migrant workers and college students come from.

This year's Spring Festival travel rush lasts for 40 days from Jan 24 to March 3.

A chart of the busiest cities during the Spring Festival travel rush. Data from China Railway Corp.