That is an interesting and difficult question. Only Iceland and Liechtenstein have honestly claimed a zero murder rate in recent years.
Once you dig deeper into the the “why” of murders, it’s clear that the problem is not uniform across all parts of the country, nor across all demographics or social classes. There are entire US states where Americans kill at much lower rates than not just the US average, but lower even the average rate in Canada and many European nations.
Maybe we should turn the question around, and ask what does it take for people not to kill? Why are there so few killings in certain regions? Why don’t Icelanders and Liechtensteiners kill?
Can we replicate the factors that make some parts of the USA less violent than other parts, or would trying to force these conditions on other states be inherently unamerican?