XIA QING, China—Like millions of children in rural China, 10-year-old Yang Hailian lives for the moment her parents come home from their jobs in a faraway city for the Lunar New Year, or Spring Festival, holiday.

Hailian counts down the days until the most important holiday on the Chinese calendar, which starts Jan. 31 this year. Factories and construction sites shut down, and most of the nation's migrant workers make the long trek to reunite with their families.

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