China has passed Canada to become the largest source of US imports last year, Bloomberg reported. Imports from China surged to US$321.5 billion in 2007, led by flat-panel televisions and computers, household appliances, toys and clothing, capping a six-year period in which China’s exports to the US have more than tripled. Chinese imports to the US are accelerating faster now than imports from Mexico did after the North American Free Trade Agreement took effect in 1994. There are concerns that the rapid increase in trade could lead to a backlash in Congress, where lawmakers have accused China of producing unsafe goods and undervaluing its currency. US lawmakers are considering measures to encourage higher duties on Chinese imports.