How have immigration, birth rates, and conversions influenced Muslim population growth in US cities between 2010 and 2025?

1. Cities on the Front Lines: Sunbelt Boom or Concentration in Traditional Hubs?

Reports point to two contrasting spatial patterns: continued concentration in traditional metropolitan hubs and rapid expansion in Sunbelt cities. One analysis projects dramatic long-term growth in Sunbelt cities such as Orlando, Austin and Atlanta—rates cited as 500% to 1,100% by 2100—and maintains New York as a hemispheric leader, but these are long-range model outputs that hinge on immigration and fertility assumptions and note vulnerabilities from climate and political instability ^[4]. Pew’s 2025 work emphasizes recent North American growth between 2010 and 2020—a 52% increase for the region—driven largely by immigration and relatively high birth rates, but it stops short of city-level breakdowns, leaving granular urban shifts inferred rather than precisely measured ^[1]. These differences matter: city planners and service providers need localized counts, not hemispheric extrapolations, because local zoning, schools and religious infrastructure depend on near-term city-scale trajectories ^{[4] [1]}.

2. Immigration: The Dominant Short-Term Engine and Its Complications

Multiple sources identify immigration as the principal proximate cause of urban Muslim population increases in the 2010–2025 window. Pew’s analyses show a majority share of Muslim adults in the U.S. are foreign-born—figures around 58–59%—indicating that migration flows directly replenish and expand urban Muslim communities, including second-generation growth ^{[5] [6]}. A 2025 synthesis and other reports link immigration surges to the 2010–2020 jump in North American Muslim populations, but authors also flag policy sensitivity: changes in U.S. admission rules, refugee flows, or global crises could rapidly alter these trends, making immigration both powerful and volatile as a driver of urban demographic change ^{[1] [7]}. The data show immigration supplies youthful cohorts and cultural diversity, yet immigration alone does not guarantee stable, evenly distributed urban growth, since settlement patterns, economic opportunities, and legal status shape where newcomers live and remain ^{[5] [1]}.

3. Fertility and Age Structure: The Quiet Multiplier Underpinning Growth

Demographers consistently point to a younger age profile and higher fertility among Muslims as a structural multiplier that sustains urban increases beyond migration waves. Global and U.S.-focused studies report lower median ages and higher birth rates among Muslim populations—Pew cites a median age of 24 globally in 2020 and highlights that a substantial share of U.S. Muslims are parents of minor children—implying that births contribute significantly to local population growth ^{[2] [5]}. Regional and long-range models emphasize that fertility sustains momentum after immigration slows by producing second-generation cohorts who grow up in American cities; one 2024–2025 projection anticipates continued outsize growth compared with some other faith groups, though the precise contribution at the city level depends on household formation patterns and assimilation trajectories ^{[8] [1]}. Policymakers should note that birth-driven growth is predictable but interacts with education, labor markets, and assimilation, altering future civic and religious landscapes ^{[5] [8]}.

4. Conversions: Visible but Numerically Limited—Still Important Locally

Conversion to Islam appears repeatedly in the literature as a consistent yet quantitatively minor factor in overall Muslim population growth. Multiple sources estimate annual converts in the low tens of thousands in the U.S., with one analysis citing around 20,000 converts per year, and Pew-era studies indicating converts comprise a meaningful minority—roughly 20–23% of American Muslim adults in some surveys—particularly among African Americans and younger adults ^{[3] [9] [1]}. Reports also stress retention issues: some studies suggest a sizeable share of new converts do not sustain mosque participation, and net conversion impacts can be offset by religious disaffiliation, so long-term population effects remain limited relative to immigration and births ^{[8] [2]}. Despite modest numbers, conversions have a disproportionate cultural and community impact because converts often bridge racial and cultural divides and influence local identity and outreach within urban Muslim communities ^{[3] [9]}.

5. Divergent Projections and What’s Missing: Data Gaps, Policy Sensitivity, and Local Detail

The available analyses agree on broad forces—immigration, fertility, and conversions—but diverge sharply in magnitudes and geographic projections, reflecting different methodologies and assumptions. Long-horizon city forecasts that predict massive Sunbelt growth depend on sustained migration and fertility trends and acknowledge climate or political shocks could alter outcomes ^[4]. Pew and other demographic reports supply robust recent trend evidence but frequently lack detailed city-by-city tabulations for 2010–2025, leaving important gaps for urban stakeholders ^{[1] [7]}. For applied planning and civil society, the critical omissions are consistent, timely local counts, longitudinal data on retention and religious practice, and sensitivity analyses for immigration policy shifts; without these, forecasts remain directional rather than dispositive ^{[7] [4]}.