Travel is fatal to prejudice, bigotry, and narrow-mindedness, and many of our people need it sorely on these accounts. Broad, wholesome, charitable views of men and things cannot be acquired by vegetating in one little corner of the earth all one's lifetime.

Mark Twain, The Innocents Abroad or the New Pilgrim's Progress, 1869, Conclusion chapter near the book's end. 

From my experience, Twain's observation could not be more true. The more people I meet traveling around the world the more I see that the differences are interesting and superficial. Basically all people want the same thing to—care for their family, make things better for their kids in the future, and to enjoy the day. It is very difficult to treat people as somehow lesser, different, or immaterial after you have met them up close. You can't treat them poorly anymore.