Today's Geo Quiz takes us to a port on the Pearl River. The Pearl River isn't quite as long as China's Yangtze and Yellow Rivers.

Still it flows 1300 miles across southern China and empties into the South China Sea. It also ranks as one of the worst polluted waterways in the world.

But we're looking for a port city on the river located roughly 75 miles northwest of Hong Kong.

Pearl River: photo http://www.flickr.com/photos/jasonbradbury

Its population of nearly 10 million swells a bit this time of year for city's annual trade fair. The fair is a place for showing off new Chinese products and for forging business deals.

trade show: photo http://www.flickr.com/photos/tjt195

And it's a chance to take the pulse of China's economy.

So name this trading hub in China's industrial heartland. We're talking Chinese imports and exports...