It is simply untrue that "getting to know people" leads to less racial and ethnic division. Familiarity breeds contempt as surely as understanding. For instance, Hutus and Tutsis in Rwanda lived together in the same neighbourhoods, yet Hutus hacked their neighbours to death in bloody genocide; or Serb and Bosniak in 1995; or Germans and the Jews in their midst prior to WWII.
What has been shown is that education diminishes racial and ethnic tension, but again depends what you are taught. If you are taught that one race is the Master, or that your land was stolen by your neighbour, inevitably that would worsen division.
It is natural for man to create an Us and Them. Even musical appreciation lines up to identity, with conservatism more likely to favour country and liberalism hip-hop and such, or ethnic musical appreciation. Often, the fact of labelling something as belonging to X, is enough to create identity differences. Studies have been done that show that even arbitrarily grouping people together for whatever reason, increases empathic response; and conversely decreases it for the outgroup individuals.