Individual sections were completed in 1949, but the model as a whole wasn't finished until 1966. By 1952, the Missouri River segment was fully operational, and information gathered from that segment helped to prevent flooding in Omaha, Neb., avoiding more than $65 million in flood damages. In 1964, the site opened to the public for self-guided tours, drawing in more than 5,000 people a year. Facilities included a 40-feet-tall observation tower, from which visitors could view the entire model.
As computer models became more prevalent and more accurate, there was not any need to keep the model running. Analysts used the Mississippi River Basin Model for the last time in 1973 to help mitigate a failure of the Old River Control Structure floodgate system in Louisiana.
The past few years have seen a renaissance of interest in the Mississippi River Basin Model. Various media outlets that focus on abandoned or hidden structures have profiled it, most notably the blog Atlas Obscura in 2015 and the podcast 99% Invisible in 2016.
Today, the Mississippi River Basin Model is open for the public to visit. If you decide to visit and explore the model for yourself, be careful: While it's still in fair condition and certainly an interesting visit, the model is overgrown with foliage. Thick pants and good shoes are a must.