The Grand Canal (also known as the Beijing-Hangzhou Grand Canal) … is the longest canal or artificial river in the world … linking the Yellow River and Yangtze River. The oldest parts of the canal date back to the 5th century BC, although the various sections were finally combined during the Sui dynasty (581–618 AD). The total length of the Grand Canal is 1,776 km (1,104 mi).
I am also not sure why you think the technology is difficult. You just dig. The traditional “technology” is slave labour.
Canals are smaller, though I grant there may be a canal which is longer than the shortest rivers.
Still, I haven’t seen proposals for canals which would be comparable to the Mississippi or the Amazon.
A quick Google, and...
I am also not sure why you think the technology is difficult. You just dig. The traditional “technology” is slave labour.