BEIJING (AP) — China’s Lunar New Year travel rush has kicked into high gear, with billions of trips expected in coming days for the peak of the 40-day annual mass migration — the world's biggest annual movement of humanity.

The actual new year holiday, which marks the start of the year of the snake in the 12-month lunar calendar, comes on Wednesday, while New Year’s Eve on Tuesday is reserved for family gatherings and traditionally fireworks displays.

Many began travelling on Jan. 14 and the rush will reach a peak over the weekend. In total, 9 billion trips — mostly by car — are expected over the 40-day travel rush.

Trips by train will surpass surpass 510 million, with another 90 million travelling by air. The government didn't say how the travel figures compared with any other 40-day period during the year.

Trips are now far more comfortable than in past years, when travelers often crammed into train cars for trips that could last days — if they were fortunate enough to buy a ticket, which are now mostly sold online.

Traditionally the festival has been a time for families to gather, with members of China’s huge migrant worker population using up all their vacation time on the annual visit that for many offers the only chance to see parents and children.

Rising prosperity and the decline in family customs in recent years has prompted those with the means to travel overseas, mostly to South East Asia, but also Japan and South Korea. Cross-border trips are expected to rise by nearly 10%, including foreign tourists willing to risk the crowds to take in the spectacle.

The government grants eight public holiday days from Jan. 28 to Feb. 4. While fireworks have been all but eradicated under President Xi Jinping, traditional events such as temple markets draped in auspicious bright red colors continue to draw visitors in their millions.