https://en.wikipedia.org/wiki/Superconducting_Super_Collider
The program was famously badly run, with talented physicists utterly refusing to work with the administrators to keep a ballooning budget under control, and was an example of utterly failed project management. It used a magnet design that had numerous problems, including really severe project management oversights, like deciding to update the magnet design, and accidentally forgetting to update a significant portion of the magnets.
Killing the SSC was the correct call. It was going to cost over $12 billion just to build. The LHC eventually cost about $5 billion, and had much more success in the world of project management.
It's a lot easier to get science funding when you can demonstrate that you can manage a several billion dollar project, and don't fuck up basic things like accounting.