The United States and Mexico border, which stretches 1,969 miles, all the way from California to Texas. This large distance between the United States and Mexico border, gives a place for illegal immigrants to possibility enter the United States illegal. With the border of United States and Mexico covering a great distance there is always a possibility of illegal immigrants coming into the United States. The issue of illegal immigration brings up many controversial issues. Some of the major issues being the threat to homeland security, the United States economy, and deportation. All of these issues are controversial meaning there are multiple sides that will be presented later. As illegal immigration has become a bigger issue over the last decade, with some wanting to take extraordinary measures to restrict illegal immigrants and others who don't believe illegal immigration is a problem. With the United States being a super power throughout the world, there’s a constant threat of terrorist attacks. The United States and Mexico border being one of the main illegal immigration spots within the United States. There is a threat to homeland security with illegal immigration becoming a bigger and bigger problem. The Center of Immigration Studies presented the data on the amount of illegal aliens in the United States, “With at least 8 million illegal aliens living in the United States and nearly one million new aliens arriving each year, the potential for terrorists entering the United States undetected is high” (Center 1). With one million illegal aliens coming into the United States yearly, there’s always a constant threat to homeland security. With these large amount of illegal immigrants coming to the United States the possibility of terrorist coming in increases and cause the threat to homeland security. From the book Risk Analysis an International Journal written by Lawrence M. Wein a Professor of Management Science, Yifan Liu an assistant Professor at George Mason University, and Arik Motskin a data scientist at Google. They presented the likelihood of terrorist entering the United State: Overall, the probability that a terrorist can successfully enter the United States is very high, and it would be extremely costly and difficult to significantly reduce it. We also investigated the alternative objective function of minimizing the flow of illegal aliens across the U.S. – Mexico border. As stated with the United States and Mexican border having a big hole for illegal aliens and terrorist to enter, there is a high probability of terrorist entering which is a major threat to homeland security. With the other side of the argument, illegal immigration and terrorist saying how illegal immigrants aren't terrorist. The American Immigration Law Foundation shared their perspective on the different between illegal immigrants and terrorists. Illegal immigrants are not terrorists. They want