There are as many as 700.000 to 850.00 people illegally immigrate to the USA yearly. This makes illegal immigration become one of the most common problems in this country. Now, it is estimated that there are more 12 million illegal immigrants living in the United State, and number can increase incessantly. These people are putting more and more pressure seriously on the government in 4 levels: social, economic, political and environmental level. Donald Trump in the first debate said “We are a nation that is seriously troubled. We’re losing our jobs. People are pouring into our country”. It shows more clearly how illegal immigration influences gravely on the USA where large numbers of immigrants have settled in relation to others, though the number of these people has been flat between 2009 and 2017. For a long time, illegal immigration has been caused sore all around the world, especially in the US. This research is aimed at giving causes, effects of illegal immigration in the USA, as well as giving possible solutions which government can put into practice to reduce this situation. 1. Discussion of findings 1.1. Background information about illegal immigration. In 1924, Congress established national-origin quotas with the Immigration Act of 1924. It granted immigration entry visas to only 2% of the total figure of residents of every nationality in the United States according to the 1890 national census. It prevented all people from settling from Asia. The World War I and strongly encouraged restricts on immigration created nervousness of people. By 1970, rate of immigration had decreased to a low of 4.7% of the whole inhabitants. That was lower from a high percentage of 14.7% in 1910. In 1965, the United States Senate changed immigration guilding principle with the Immigration and Nationality Act. It got rid of allowance relied on nationality. Instead, it supported people with essential skills or who were going in with families in the United States. This made an increasing in immigration from Asia and Latin America (The Wall Street Journal, April 11, 2017). In 2014, 1.3 new people immigrated to the United States. This number went up from 1.2 million in 2013. Today,the rate of people who immigrated to America is quite similar to the number in late 19th century, when almost 15 percent of U.S residentswere immigrants. Most of them came from Italy, Germany or Canada. The Department of Homeland Security (DHS), in a Feb. 2011 stated that: ” The unauthorized resident immigrants population is defined as all foreign-born non-citizens who are not legal residents. Most unauthorized residents either entered the United States without inspection or were admitted temporarily and stayed past the date they were required to leave”. Illegal immigration (also related to unlawful or unconfirmed immigrants) can be defined that the relocation of individuals across countries borders in a way which damage the immigration laws of the predetermined nation (The Center for Media and Democracy, August 10, 2008). Nowadays, illegal immigration is a serious trouble that numerous of countries have to face to, include the USA – the most severely affected nation. There are four common forms of illegal immigration (Demetrios G. Papademetriou, 2005). The first is undocumented or unauthorized entrants, nationals of one state who enter another state covertly. The second is individuals who are checked to entry into another state, but get entrance by fake texts. The third is violators of the time of a visa, which include individuals entering another state but overstay for a illegal period of time. The final is violators of the terms and conditions of a visa. It means that nationals of one state who entry into other state with the proper texts and procedures, but at some point violate the terms of their visa.