TIL about the Mississippi River Basin Model (https://en.wikipedia.org/wiki/Mississippi_River_Basin_Model) - a detailed 1:2000 model of the 30-state large basin. The model was built mostly with labor of the Japanese POWs in the 40s, occupies 200 acres (= 2.5 Disneylands), and 600 researches who worked there were able to predict water level during major event with 2-inch accuracy.
There's also the San Francisco Bay Model (https://en.wikipedia.org/wiki/U.S._Army_Corps_of_Engineers_Ba...) which is only 320x400 feet, with different horizontal and vertical scales. It was used to reject a Bay Area dam proposal in the 50s. The model is currently on display in Sausalito. ‎· Valera Fooksman