Format: | "Immigration has been a controversial topic throughout American history. Debates about whether or not immigrants adversely affect the American economy, exacerbate crime, threaten American values and quality of life, and should or should not be allowed into the country existed since the first European settlers came to America. However, these controversies intensified during the last four decades of the 20th century and spilled over into the 21st century because American laws allowed mass immigration to occur despite growing environmental, social, and cultural concerns"-- |