We are attached to our guns. It's a cultural thing that dates back to the founding of the country. Many of us believe (us as in Americans, not us as in me too) that this is protection from our own government, and it is enshrined in our Constitution in the second amendment for that reason. Some also feel that it preserves us from invasion as no one could possibly fight against millions of armed civilians.
The fear of crime is a self fulfilling prophecy. We buy guns to protect ourselves from criminals who steal the guns and use them to commit crimes. Then more guns are bought and more are stolen, and it keeps on growing. With response times of over an hour when calling police in an emergency, people feel pretty helpless in many areas and get guns to protect themselves. And in some areas this is necessary.
There are almost no laws prohibiting people from having guns, and many places have very liberal laws for carrying them in public.
The high murder rate is kind of skewed, in that most of the murders occur in the same places (large urban areas), while most of the country is very safe. The city of Detroit alone has more homicides than some countries have in a civil war.
The school shootings have been sensationalized, and the actual homicide rate has been declining in schools (like schools should have a homicide rate to begin with, but that's us, a very violent culture) for a decade. The more the news talks about it, though, the more "copycat" crimes we have.
So, in conclusion, it "seems" that way because it is an accurate reflection of reality. One of the many reasons I like to communicate with people from other countries and cultures. Sanity is in short supply here.