America's Youngest Cities — and the Three Forces That Create Them

The median American is 38.7 years old. In Kiryas Joel, NY, the median resident is 15.1 years — not the median adult, the median person. Half the city is younger than a high-school sophomore. We ranked every US city with at least 20,000 residents by median age, and the young end of the distribution turns out to be far stranger and more interesting than the old end, because cities get old in basically one way but become young in three completely different ways.

38 of the 100 youngest cities have median ages under 25, a figure no natural aging process produces. Each one is the result of a specific engine — extraordinary birth rates, a university, or a magnet for young families — and the engine is usually identifiable from the table alone.

The 100 Youngest US Cities

Limited to places with at least 20,000 residents.

Source: U.S. Census Bureau, American Community Survey (ACS) 5-Year Estimates.

Force One: Birth Rates Without Modern Parallel

The cities at the very top of the list — Kiryas Joel and Monsey among them — are communities with birth rates far above any US norm, dominated by large religious families in which children outnumber adults. In Kiryas Joel, 56.9% of all residents are under 18 (nationally: 22.2%). Median ages in the teens are demographically impossible any other way: no volume of young-adult migration can drag a median that low, because migrants arrive in their 20s, not at age zero.

Forces Two and Three: Campuses and Cribs

The second cohort clusters in the early 20s and is instantly recognizable by its 18–34 column: college towns, where tens of thousands of students compress the age distribution around 20. Nearly all of them also appear in our data-defined college towns list. The third cohort fills out the rest of the table in the late 20s and low 30s: fast-growing suburbs — many in Utah, Texas, and the wider Sun Belt — that attract young families with affordable new housing, pairing high under-18 shares with high shares of adults in their 20s and 30s.

The three types diverge sharply in economics. Family boomtowns post solid middle-class incomes; college towns post artificially low ones; and the highest-birth-rate communities often post very low measured household incomes spread across very large households. A young median age, in other words, is not one phenomenon but three — and the state-level contrast is visible in the oldest states ranking, whose bottom entries are driven by exactly these forces.

How We Did This Analysis

Every US place with at least 20,000 residents was ranked by ACS median age, ascending. The under-18 and 18–34 population shares are shown to distinguish the three mechanisms discussed above. Median age refers to all residents, not adults.

All figures come from the U.S. Census Bureau's American Community Survey (ACS) 5-Year Estimates. Because estimates pool five years of survey responses, small differences between closely ranked entries may fall within the survey's margin of error. Learn more on our methodology page or at data.census.gov.