The first ten Amendments to the United States Constitution, commonly known as the Bill of Rights, is the highest law of the land. If for some reason you happen to disagree with me about that (probably because of your public "education"), and with the Founding Fathers and the Supreme Court, there's no point in your reading further. Put it cybernetically, the Bill of Rights is the basic operating system of the country and the sole source of American exceptionalism. If we don't have that we have nothing. We might as well be Belgium.
The Second of those Amendments famously maintains that the government may not interfere, even in the slightest, with the individual right to own and carry weapons. Lesser lights than the Founders over the centuries have been absolutely terrified at the idea of a well-armed populace ("Your people, sir, are a great beast!" said Alexander Hamilton), and have attempted desperately to limit that right and gradually whittle it away.
The most pertinent and obnoxious example of that (only one of many) is the 1911 New York Sullivan Act, named after an infamously corrupt Tammany Hall (look it up) politician, meant primarily to disarm Italian immigrants that politicians were frightened by. The law was so egregious that even notorious gun-grabber Wyatt Earp questioned Sullivan's mental health. .....