Many Americans, including Donald Trump, are concerned over whether Muslim immigrants and their descendants are assimilating into American society. This topic is tricky for a few reasons. First, almost all Muslims who are immigrants or descended from them entered the United States after 1968 so there haven’t been many generations yet. As a result, the evidence and research on Muslim assimilation are not as complete as they should be. A second problem is that many studies or surveys do not compare the opinions of Muslims with society at large or other minorities. Where possible, such comparisons will be made below. A third problem is that, until recently, sociologists weren’t interested in Muslim assimilation in the United States. Whereas there is a vast literature on Hispanic assimilation going back generations, Muslims were overlooked entirely prior to the 1990s.
To mix my personal experience with this post, my brother and I are two of a handful of third-generation descendants of Muslim immigrants. Our paternal grandparents came from Iran in the late-1940s while our maternal grandparents were the descendants of Europeans. Nobody on that side of the family identifies as a Muslim anymore let alone practices, as far as I know, and none of those who were born Muslim raised their children as such.
My wife and her family have a similar experience although her father was born a Muslim and immigrated here in the 1970s. The extended portions of my family and my wife’s family mostly immigrated after the Islamic Revolution in 1979. Thus, I am deeply interested in this topic for personal as well as professional reasons.
The United States government does not ask Americans or immigrants about their religious beliefs, with the exception of refugees. Thus, we have to rely on private surveys and other methods of estimating the Muslim population in the United States. Many of these surveys do not distinguish between different sects of Islam but merely on self-identification. Thus, a Sunni Muslim immigrant from Saudi Arabia is just as Muslim as an African-American convert to the Nation of Islam.
A 2015 Pew Research Center report estimated that there are roughly 3.3 million Muslims in the United States equal to just over 1 percent of the population – up from Pew’s estimates of about 2.4 million in 2007 and 2.6 million in 2010. The U.S. Religion Census (not be confused with the U.S. Census Bureau) in 2010 found that there were 2.6 million Muslims, equal to about 0.84 percent of the U.S. population.
Seven of the most methodologically sound estimates of the size of the Muslim population around the turn of the Millennium found there to be between 1.5 million and 3.4 million Muslims in the United States. Five of those seven estimates found that there were between 2.3 and 2.9 million Muslims. Compared to the more recent estimates by Pew and the U.S. Religion Census above, the Muslim population has grown slowly.
Births and immigration are the main sources of growth for the Muslim population. Pew in 2011 estimated the total fertility rate (TFR) of Muslim women in the United States to be 2.5 children per woman and just 2.2 for Muslim women born here – both above the U.S. TFR of 1.9 in 2011. Roughly 5 percent of the stock of immigrants in the United States is Muslim. One Pew paper estimates that 80,000 to 90,000 immigrants a year are Muslim while another found 115,000 a year in 2009. Pew estimates that there will be 6.2 million American Muslims by 2030 that comprise 1.7 percent of the population.