Black and white half-body portrait paintings of forty-two children line the front of the French Pavilion at the Shanghai World Expo. The children show a variety of expressions -- smiling, crying, frowning... -- and are dressed in simple clothes.

"Children of Shanghai," a work of 21 painted stainless steel panels, is an artwork by local artist Yan Peiming.

All the children's parents are migrant workers who worked on the construction of the pavilion, said Zheng Lan, a staff member of the French Pavilion.

Yan Peiming said the children, who came from the countryside to Shanghai with their families, are part of a rural exodus that has lead to the city's population explosion.

There is a need for the general public to understand the problems of urbanization in a country with 200 million migrant workers, said Yan.

Statistics show that by the end of 2009, China's urbanization rate reached 46.6 percent. It's estimated that another 400 million people from rural China will migrate to cities in the coming 20 years.

Farmers leaving their land to reestablish themselves in urban areas face numerous problems in China, such as identity issues and lack of rights compared to urban residents.