Immigration sometimes becomes mandatory for the individuals who seek new employment opportunities, education, religious matters, family re-unification, poverty, natural disasters etc. People from poor countries migrate to more developed nations for better standard of living and more financial freedom. After the formation of United States in 1776 there were very few immigrants existing in the country, but the immigration rate grew drastically during the period of 1836 to 1914 with over 30 millions of Europeans migrating to US, by the percentage ranging between 12.0 to 15.0 percent of the total population.
Due to the Immigration Act of 1924 and great economic depression many people emigrated from US rather than migrating to it and the rate dropped to 11.6% at the end of year 1930. However, after the amendment of new immigration policies and abolishing the national origins quota system through Immigration and Naturalization Act in October 1965, the immigration rate started increasing due to large scale of migration from other non-European nations like Latin America and Asia.
As a percentage of US population, the immigration rate has more than doubled from 4.7% in 1970 to 10.4% in 2000 because of the favorable living conditions and vast economic growth. The decrease in the transportation costs, easy travel facilities, economic expansion and technological development are some of the key factors that have facilitated easy immigration and increased the resident population of US to 226,545,805 by 1980s. As per the 2000 census, there are about 28.4 million immigrants residing in the United States which is considered as the peak number than ever before in the history.
The economic and job recession in the recent years lowered the immigration rate and based on the census bureau it almost remained same for the three consecutive years of 2007, 2008 and 2009. It is estimated through the statistics that sixty percent of the growth in US population between 1994 and 2050 is because of immigrants and their future generations. As per the statistics of United States Citizenship and Immigration Services an estimated 12.6 million legal permanent residents lived in US by the end of year 2010. This data is inclusive of total naturalized citizens and non-immigrants and foreign born nationals.
Despite of the efforts made by federal government to remove the unauthorized immigrants, the illegal entries remains steady in 2011 at 11.2 million without any change from the previous year. As of today, Mexico is considered as the top most country to send more immigrants to US with highest percentage when compared to other nations. With this gradual increase in the immigration rate and steady growth in the birth rate, the US population is expected to become double about 600 million after 7-8 decades.