The population of the USA has grown by an average of 1% per year for the last twenty years., or about 3 million persons per year. A growth rate of 1% per year means that it would take approximately 100 years for the population to double. For comparison the global population grew about 400% from 1.5 billion to 4 billion from 1900 to 2000. It seems reasonable to say that 1% population growth should not be considered rapid or extreme.
According to the Pobulation Research Bureau(1),
“Between 1990 and 2010, the number of foreign-born U.S. residents almost doubled from 20 million to 40 million, while the U.S. population rose from almost 250 million to 310 million. Thus, immigration directly contributed one-third of U.S. population growth and, with the U.S.-born children and grandchildren of immigrants, immigration contributed half of U.S. population growth.”
The following table(also from the PRB) breaks down immigration to the US in more detail:
Entries In and Out of the United States, 2005-2009
|Immediate relatives of U.S. citizens||436,231||580,348||494,920||488,483||535,554|
|Other family-sponsored immigrants||212,970||222,229||194,900||227,761||211,859|
|Refugees and asylees||150,677||216,454||136,125||166,392||177,368|
|Diversity and other immigrants||75,617||88,017||64,294||57,979||62,003|
|Legal Temporary Migrants||32,003,435||33,667,328||37,149,651||39,381,925||36,231,554|
|Foreign students (F-1)||621,178||693,805||787,756||859,169||895,392|
|Temporary foreign workers||882,957||985,456||1,118,138||1,101,938||936,272|
|Illegal Immigration: Apprehensions||1,291,142||1,206,457||960,756||791,568||—|
|Removals or deportations||246,431||280,974||319,382||358,886||—|
|Change in unauthorized foreigners||572,000||572,000||572,000||-650,000||—|
We see that legal immigration to the US contributes at most 0.3% population growth on average. Adding illegal immigration to this would put the total contribution of immigration to population growth at about 0.5% a year on average.
The following chart (created by the PRB) shows the annual number of legal U.S. immigrants by decade over the last fifty years:
If legal immigration were to continue at a rate of about one million persons per year, it would begin to shrink as a factor in total population growth.
Population Research Bureau, Immigration in America 2010 http://prb.org/Publications/PopulationBulletins/2010/immigrationupdate1.aspx