<human>:  Why is the US's foreign exchange reserves larger than China's?
<bot>: The US has more foreign currency reserves than China because the US is a much larger economy. The US has a GDP of $19.5 trillion compared to China's $12.5 trillion. The US has a larger population of 325 million compared to China's 1.35 billion. The US has a larger trade deficit than China, and therefore needs to hold more foreign currency reserves.