Zero conditional uses simple

We use the zero conditional when we want to talk about facts or things that are generally true. Scientific facts are often covered by the zero conditional: "When you heat ice, it melts." The zero conditional uses if or when and must be followed by the simple present or imperative.

because of all the immigration, america became one big melting pot. the diversity of cultures from all over the world made america somewhat divided as well. people that immigrated stayed with their kind, and their traditions, while native born americans stayed with their kind and their traditions. normally, people born in american scorned the immigrants as well. the new religions also divided america. in summary, it took away from the american culture and identified america as the "melting pot."