Okay...I do get the joke. It's not funny, but I get it. And not to be a humorless fuddy-duddy, but the given rampant ignorance regarding South Dakota recently on shocking display, I feel it is my duty as a South Dakotan to explain something:
The reason that the faces are grouped like that on Mount Rushmore is that that's the only way they could make them all fit. After they had to move Jefferson to Washington's left because of unsuitable rock on his right, they had to redesign the whole monument so that all four faces would fit and that they would be visible and so that they could avoid any naturally occurring cracks in the rock as much as possible, because the cracks could undermine the structural integrity of the sculpture. So if there appears to be a space, it's because that space could not be used in the sculpture. It's essentially dead space.
Also, there's a large crevice just behind the faces of Mount Rushmore. Most people don't know about it because it's not very visible from the road(s). But when they were carving Roosevelt, for example, there was a danger of blasting too much or drilling too deep and punching through the backside of the mountain. I forget exactly how close it came, but I believe it's within several hundred yards.
To reiterate, there is no more room for any more carving on Mount Rushmore!!! I know that the Trump administration is not fond of facts, but this is one that is LITERALLY set in stone.
As for the comedians, wait until they find out that when it rains at Mount Rushmore, it makes quasi-tear streaks on the presidents' faces.