“The constitution [of 1787] … rested upon the assumption of the equality of races. This was an error. … Our new government is founded upon exactly the opposite idea; its foundations are laid, its corner-stone rests, upon the great truth that the negro is not equal to the white man; that slavery subordination to the superior race is his natural and normal condition. … In the conflict thus far, success has been on our side, complete throughout the length and breadth of the Confederate States. It is upon this, as I have stated, our social fabric is firmly planted ….”
Quote from the “cornerstone speech” by Alexander Stephens, vice president of the Confederate States of America, on March 21, 1861 (complete text here). The many Trump supporters who fly Confederate flags from their vehicles may not realize it, but this is what those flags stand for.