Beijing's municipal government announced April 25 that will issue 600,000 free multifunctional identity cards to migrant workers in the city's construction industry in 2007. Large construction projects that last for longer than six months in duration, cover more than 5,000 square meters (about 54,000 square feet) or cost more than 5 million yuan (about $647,000) are obliged to provide at least 95 percent of their migrant workers with this card. Migrant workers can use the cards for banking and as an identity document. The program's stated objective is to prevent nonpayment of wages, a key source of urban social unrest.