In the old days, grain from the south was shipped to Beijing along the Grand Canal.
Tips
history
The oldest section, the 邗沟 near Yangzhou, was dug in 486 BC. The Sui joined the river systems into one network, and the Yuan cut a straighter route north to Beijing. For centuries it carried the south's tax grain to the capital, and in 2014 it became a World Heritage site. It is often called just 大运河.
memory
京 stands for 北京 and 杭 for 杭州: the name gives the two ends, like 京沪 for Beijing and Shanghai.