As a child pouring over National Geographic at the library with my friends, we giggled at the naked pictures of tribespeople from Africa, the Amazon, South Pacific, or other parts of the world. We turned quickly to a picture of an animal if the librarian walked by.
We humans are social animals and bond with like-minded people. Throughout history, there were tribes and as the populations grew these tribes became nations. Our country is one of those nations and we welcome people into our country. We are the "melting pot" as all these immigrant cultures meld together to form America's traditions and ideals. Canada promotes multiculturalism but we encourage different cultures to assimilate and become part of our unique culture.
The world today is more complex. The biggest problem of the 21st century is mass migration throughout the world. It causes many challenges such as changing a country's demographics , culture, and political economics. Unlimited mass migration (open borders) could cripple the United States in many ways and lessen our influence in the world. This could benefit both Russia and China who have different views on open borders and human life.
Many people applaud the diversity of people as a good thing. They may give the example when they were in college that they lived with people from different parts of the world. But for the most part these other students were screened before admitted to the college. Many of their ideas and beliefs were similar. In a mass migration, you will have various ideas that are considered normal. Some people feel that "honor killings" are justified. A woman may be killed to protect a man's "honor". The age of consent for marriage or sexual relations are differnt among different cultures. India is one of the most diverse countries in the world. There have been mass migrations on the sub-continent for years. Yet with so many different cultures and groups there is much unrest.
Open borders are not the answer and can lead to unwanted goods (drugs) and unwanted people (criminals and gangs) from entering our country. Usually these people are poorer and unskilled. They rely on the welfare of the country . They are drawn to America for the "free" benefits provided. All this increases the national debt. America needs to welcome immigrants but at the same time screen these people.