Immigration, Immigration...wherefore art thou immigration?

Bryson (pre-Brexit/Dfrumpf) on immigration: "...if you think the only people you should have in your country are the people you produce yourselves, you are an idiot..." Comment?   

I am a firm believer that immigration is necessary for the growth and development of a nation. The United States of America for example is one of the greatest, most powerful countries on the planet currently. What this translates into is that some of the best and brightest choose to immigrate to America. Immigrants that called America home include Madeleine Albright, Arnold Schwarzenegger, Hakeem Olajuwon, Joseph Pulitzer, and (arguably) most famous of all Albert Einstein. While this list only represents a few of the countless immigrants that have ventured to America and called it home, it shows how vital immigrants are to the new ideas, developments, and the continued success of a country. Imagine for a second if all the 1^st generation immigrants in America mysteriously disappeared tomorrow. The country’s economy would go into a complete free fall.  America was founded on immigration and cannot survive without it. America is a country that was built upon the concept of free labor and with many immigrants they are getting a substantially reduced rate on their labor force. Yet, beyond that the beauty in America is its claim of heterogeneity. It is rare that you see successful states that promote homogeneity. For example, China and Japan are both nations that strongly and visibly promote homogenous cultures, and they rank number second and third in the world’s economy respectively. However, the number one economy is still the United States of America. And so I agree with Bryson’s assessment that it is short-sighted and illogical to only want a country of people that are produced by that country. It cuts off a significant supply of labor, talent, ideas, taxes, and experiences. One thing that immigrants do is they bring parts of their culture to their new found homes. I believe that there is power in having vastly different cultures under one flag. It helps to see small pieces of the world every time you step out your front door.