I went on a Wikipedia ramble and read last night before bed. A very enjoyable before bed activity on a weekend.
Started with a friend on Facebook talking about Duff’s Ditch as a solution to the flooding problems in Fargo, ND. Duff’s Ditch is otherwise know as the Red River Floodway around Winnipeg, MN. At the time (1968) the Red River Floodway was was the second largest earth movie project of all time. In front of the Suez Canal and the behind the Panama Canal.
The Red River Floodway cost $360 million CAD to move 305 million cubic yards of earth. CAD $1.18 per cubic yard.
When the US bought the Panama Canal from the French they paid $24.4 inflation adjusted USD per cubic yard. To finish the canal the US paid $6.1-$12.2 per cubic yard for dredges and $12.2-$24.4 per cubic yard for steam shovels.
Picture of the Yellow Fleet from here
I used this tool to calculate approximate inflation adjusted dollars.