Muslims are not terrorists. Some of them are crazy with their religion and they want everybody to be Muslims. People from ISIS are terrorists but they are killing other Muslims too.
Having a Cultural diverse space in the United States can help us interact with others to build trust, understanding and respect to other cultures. Having a diverse and inclusive community helps with preventing more personal biases, negative stereotypes, racism and bigotry from occurring. It also helps build a more safer and stronger community.
The southern part of the United States is heavily influenced by the sea/ocean and the wind patters that occur because of it. The warm waters that surround the region are making it more stable temperature-wise and the weather is warm and wet for big portions of the year. The precipitation is high as well. But this also brings in problems in the shape of the hurricanes, tornadoes, intense big rainstorms, and floods.
The creation of approximately ten million refugees from 1947-48 was a result of World War II.
World War II brought destruction of lot of countries, millions of people lost their homes that were flattened with the ground, the economies were destroyed and on the verge of bankruptcy, so millions of people left their countries in search for better life (or rather just normal life).