One big barrier is economic background. Many students from immigrant parents often can’t afford college or have to work instead of going to school. Another difference can be the language barriers given that it’s harder to learn English than it is most languages because it doesn’t stick to grammar rules as much as others do.
I am not sure what exactly you want to receive as an answer but Ill give 2 examples.
After the rise of the Third Reich Jewish people were forced to migrate from Germany to neighboring countries and a lot of them in fact fled to United States including the famous scientist Albert Einstein.
The other example is the forced migration of Native Americans during the settlement and colonization by the American Colonies as they were trying to go farther down the continent.
20 increased by 12.5% is 22.5