Muslims will replace Jews as the United States’s second-largest religious group by 2040, according to projections by the Pew Research Center.
While there is no official count of either religious group since the US Census doesn’t ask Americans about their religion, private surveys of the American population allow researchers to estimate the numbers of Americans who identify with each group.
Muslims currently make up some 3.45 million people living in the US, or about 1.1 percent of the total population, while a major Pew study last year suggested some 6.7 million Americans, or 2.1% of the population, identify as Jews.
But that gap is unlikely to last, the group said in a statement Wednesday, explaining that “our projections suggest that the US Muslim population will grow much faster than the country’s Jewish population.”
The Muslim share in the overall US population has grown quickly, from 0.4% of all Americans in 2007 to 0.9% in 2014, according to a previous 2014 study by Pew. Jews’ share grew too, but more slowly, from 1.7% to 1.9% in the same period.
The fastest-growing religious identity in the US is “unaffiliated,” which grew by 6.7 percentage points in just seven years, from 2007 to 2014, from 16.1% to 22.8%.
Christians, meanwhile, declined by 7.8 points, from 78.4% of the US population to 70.6% in those years. The decline is sure to continue, as older Americans are far more likely to identify as Christian (85% of those born before 1945) than younger Americans (57% of those born in the 1980s).
Similarly, just 4% of Americans born before 1945 identified with a non-Christian religion, including Jews, Muslims and Hindus — a figure that jumps to 8% among those born since 1981.
The Jewish population appears likely to go the way of Christians in the country, Pew’s surveys in recent years suggest. Overall, according to the 2014 survey, the American Jewish population is expected to grow slowly until roughly 2030, after which it will begin to shrink due to low birthrates and changing religious identification.
The Muslim population, meanwhile, driven largely by birthrate and immigration, is expected to rise quickly. It grew from an estimated 2.35 million in 2007 to 2.75 million in 2011, and continued to grow since then by roughly 100,000 each year.
“By 2050,” Pew’s Wednesday statement said, “the US Muslim population is projected to reach 8.1 million, or 2.1% of the nation’s total population [at that time] — nearly twice the share of today.”
As with Jews, Muslims are concentrated largely in coastal states like New Jersey and New York. Continued population growth will thus be more evident in some places than in others.
Pew also found that conversion plays relatively little role in Muslim growth. While large numbers of American Muslims — about one-fifth of adults — converted to the religion from a different one, a similar number who grew up in Islam left it as adults, leading to almost no change in the overall figures.