How does the US Muslim population compare to other religious groups?

1. Different counts, different methods — why numbers diverge

Scholars and advocacy groups report different totals because they use different methods: congregation-based counts such as the U.S. Religion Census produced a 4.5 million figure in 2020, survey-based estimates (Pew and others) have produced lower counts (about 3.45 million in 2017 and other surveys placing the adult or total Muslim population near 3.8 million), and private compilations produce still other estimates ^{[3] [1] [2]}. These methodological differences—whether researchers count mosque membership, self-identification in surveys, or adjust for undercounting of immigrants—explain most of the discrepancy ^{[3] [1]}.

2. How Muslims rank compared with other U.S. faiths

Historically and in widely cited snapshots, Christianity is the dominant U.S. faith (older Pew summaries put it at about 70% of Americans), unaffiliated people are a large and growing group, and Muslims are a small minority usually reported as the third-largest organized religion after Christianity and Judaism in some sources, though exact ranking depends on which estimates you accept ^{[1] [3]}. Some sources say Islam is the third-largest religion in the U.S.; others show similar-size totals for Hinduism or Buddhism when different counting methods are used—available sources do not provide a single unified ranking that reconciles every dataset ^{[1] [3] [2]}.

3. Demography: younger, more diverse, and concentrated

Multiple profiles describe American Muslims as younger and more ethnically diverse than many religious groups: one recent profile finds 26% aged 18–24 and describes roughly one-third Black, one-third South Asian and one-quarter Arab composition, with 42% U.S.-born in one report ^{[3] [4]}. Geographically, the largest raw Muslim populations cluster in major states and metros—New York, California, Illinois, New Jersey and Texas show the biggest state totals in several 2025 compilations, and the Detroit metro area is often cited as having the highest concentration ^{[5] [6] [7] [1]}.

4. Institutions and civic footprint

Reports note thousands of mosques and hundreds of Islamic schools in the U.S.—figures like roughly 2,700 mosques and about 300 Islamic schools are cited—indicating organized community infrastructure even where the absolute population share is modest ^{[1] [4]}. Muslim Americans also appear in business and professional sectors at measurable rates (e.g., counts of Muslim-owned businesses in New York City and estimates of Muslim physicians), showing that community presence extends beyond worship into civic and economic life ^{[4] [3]}.

5. Growth outlook and international context

Globally, Islam is among the fastest-growing religions, and projections show sizeable growth through 2030–2050; some commentators point to similar growth dynamics in the U.S. because of younger age profiles and ongoing immigration, though projections vary and depend on fertility, conversion and migration trends ^{[8] [3]}. That said, U.S. estimates remain sensitive to data source choice—some projects emphasize faster growth, others are more conservative—available sources do not produce a consensus growth rate specific to the U.S. beyond noting youth and immigration as drivers ^{[8] [3]}.

6. Competing perspectives and the agenda beneath the numbers

Advocacy groups and community organizations often use higher estimates (e.g., the 2020 U.S. Religion Census’s 4.5 million) to argue for greater visibility and resources; some academic or survey-based groups produce lower figures and emphasize methodological caution ^{[3] [1]}. That divergence can reflect implicit agendas: higher counts bolster claims for representation and services, while lower counts are sometimes cited in discussions about assimilation, security or demographic impact. Readers should treat single-number headlines with skepticism and check which methodology is being used ^{[3] [1]}.

7. What reporting leaves out or still needs clarity

Available sources disagree on a single, authoritative U.S. total and do not reconcile all methodological differences; they also vary in how they compare Muslims to all other faiths in the same year using identical methods ^{[3] [1] [2]}. For a definitive cross-faith comparison using one methodology, readers should consult the original datasets (U.S. Religion Census, Pew surveys, large-scale survey vendors) and note whether the figure counts congregational affiliation, self-identification, age cohorts or immigration status—sources provided here do not contain a single reconciled table that answers every comparative question ^{[3] [1]}.