Mother-in-law keeps insulting my race.

My wife's mother keeps saying mean things about men and women from USA. Basically, she dislikes americans because of what she sees in the media about our racism issues and attitudes during distressing times. I try to convince her that every country has problems like that with locals and people in all shapes and sizes but she just won't listen. She believes that all americans are gun-loving and racist freaks that do nothing but spread war and hatred. How can I convince her otherwise? I'd love to have a great relationship with her but I don't see that happening.