The United States is an ethnically diverse country. If you separate out the European ethnicities, you find that they have homicide rates that are similar to those in Europe.
http://gunwatch.blogspot.com/2013/01/european-murder-rates-compared-to.html
http://gunwatch.blogspot.com/2013/01/european-murder-rates-compared-to.html
More fun with statistics.
If you adjust the Non Hispanic White homicide rate by removing homicides related to Non Hispanic Whites defending themselves from assaults, muggings and other criminal behavior perpetrated by Blacks and Hispanic Whites, the Non Hispanic White homicide rate drops below that of most of Europe and begins to approach that of Japan.