Sandy's fan Troy Smith wrote;
An internet search last night revealed that 1918 Broadway, Mt. Vernon, was currently used as Auto Mart. I thought that could be a good sign that this was an original Sandy's building. Sandy's buildings sometimes end up as used car lots, probably due to their footprint. With no satellite images to go off of, I thought I might strike gold on this one. That wasn't the case. In fact, this is one is an odd shape, even for a Hardee's. I peeked inside, but nothing resembled a restaurant, let alone a Sandy's. It appears the original Sandy's was stripped to the bone, or rebuilt entirely, upon conversion to Hardee's.
If you have any memorabilia, pictures or stories of Sandy's in Mt. Vernon, Illinois or elsewhere, please email me!