To eliminate the tornado threat for the entire Tornado Alley, we may need to build three great walls. The first one should be close to the northern boundary of the Tornado Alley, maybe in North Dakota. The second one should be in the middle, maybe in the middle of Oklahoma and going to east. The third one can be in the south of Texas and Louisiana. As a proof of concept, we can build the 3rd wall first on the Texas/Mexican boarder. Yeah, that is the ticket. Get all the great plains states to join with the boarder states to get it done.
We are saving lives!