A children's geography of New York · 65+ map · where they overlap

Where the children went,
1970 to 2023

In 2023, the five boroughs had 490,000 fewer children under 18 than in 1970 (−22%); the bordering inner-ring counties in New York and New Jersey had 443,000 fewer (−27%). A few points of context: 1970 was the national baby-boom peak, and the U.S. under-18 count is up only 5% since (69.7M → 73.1M); the region's total population grew by about 1.1 million (+9%) over the same span; and the region's under-18 count has been roughly flat since 1990 (+8%). The map below shows where the change landed by neighborhood — losses are uneven, and a handful of neighborhoods more than doubled.

Age group
Measure ?
View Map colors show change in density between two years.
Years or pick → Scrub end year

1970→2023

Change in children per square mile, by 2010 census tract. Red = gain, blue = loss, white = within ±10%.  ·  Click a or for the story behind a notable tract.
Classroom view

The schools they attend have been shrinking, too

85 years of K–12 enrollment, across every sector — traditional public, charter, parochial, independent, and homeschool.

Traditional public Charter Religious / parochial Independent (secular) Homeschool
Stacked K–12 enrollment in the five boroughs, 1940–2025. Pre-2000 values are historical estimates; post-2000 are direct state and city reporting.
1.55M
Peak K–12 enrollment (1970)
1.22M
K–12 today (2025)
−21%
Change since the 1970 peak
Since 2019
Kindergarten enrollment is down 22% and grade 1 down 20% — the steepest drops are at the front end of the pipeline, not in the high-school grades, which points to fewer births and out-migration of young families more than dropout or high-school exodus.
Chronic absenteeism
The share of students missing 10%+ of school days rose from 26.5% pre-pandemic (2018–19) to a post-pandemic peak of 40% (2021–22), and still sits at 33% in the preliminary 2024–25 Mayor’s Management Report.
Sources: NY State Education Dept., NYC Independent Budget Office, DOE InfoHub, NYU Research Alliance for NYC Schools.  Extended view and methodology at the NYC enrollment project.
Methodology

Data. Decennial census counts of persons under 18 (NHGIS time-series table D08, "Persons by Age: Children and Adults") for 1970, 1980, 1990, 2000, 2010, and 2020. American Community Survey 5-year estimates (B01001, sex by age) for endyears 2011 through 2023. Each year between 2011 and 2023 is a measured ACS estimate, not an interpolation. Pre-2011 years between decennial anchors are linearly interpolated.

Age-group filter. The "Age group" chip row lets you restrict the map, totals, and ranked lists to one of four bands: under 5, 5–9, 10–14, or 15–17. Age-band counts come from decennial table P012 (2000 and 2010 SF1), P12 (2020 DHC), and ACS table B01001 (2011–2023) — the under-18 totals used everywhere else are sums of the same underlying variables. Because NHGIS time-series table D08 only splits persons into "under 18" and "18+", the age-band view is only available from 2000 forward; pre-2000 years and the 2001–2009 gap between decennials are simply not in the dataset. Age-band numbers are never interpolated — every reported year is a direct measurement.

Geography. The study area is the five boroughs of New York City plus every county sharing a land or water border with NYC: Westchester and Nassau (NY); Bergen, Hudson, Union, and Middlesex (NJ). Everything is rendered on 2010 census tract boundaries. Tract polygons are clipped against TIGER/Line AREAWATER (rivers, harbor) and AREALM (parks, cemeteries, airports, and military installations) so non-residential land is not painted by the choropleth. Neighborhood labels in the ranked lists come from NYC Planning's 2020 Neighborhood Tabulation Areas (inside the five boroughs) and TIGER PLACE 2020 (incorporated and census-designated places elsewhere).

Normalization across decades. Tract boundaries are redrawn every decennial census, so 1970, 1980, 1990, and 2000 tracts are not the same shapes as 2010 tracts. To compare apples to apples, each historical decade's counts are redistributed to 2010 tracts using an area-weighted crosswalk: for every historical tract we compute the geometric overlap with each 2010 tract it touches, and allocate its child count proportional to the area overlap. Historical tract polygons come from NHGIS (table extract #2, shapefiles US_tract_1970 through US_tract_2000). After redistribution, decade totals match the raw NHGIS sums within rounding - the redistribution doesn't change the regional total, it just moves counts between tracts that were split or merged. This is a geometric approximation; a fully population-weighted crosswalk (using 2010 block populations to decide where a split-tract's people actually lived) would be marginally more accurate but requires an additional step not yet implemented.

Density. Children per square mile = count ÷ land area in sq mi. Land area is computed from 2010 TIGER cartographic boundaries projected to EPSG:2263 (NY State Plane, Long Island, survey feet). Tracts under 0.005 sq mi (airports, parks, water) are excluded.

Share under 18. The "Share under 18" measure divides the count of children under 18 by the tract's total population and reports the result as a percent. This controls for population density — a tract with a lot of kids and a lot of adults has the same density score as a tract with a lot of kids and few adults, but a different share score. Denominators come from decennial table P012/P12 (2000, 2010, 2020) and ACS table B01001 (endyears 2011–2023), interpolated linearly across the 2001–2009 gap. Because pre-2000 totals aren't available in the same pipeline, the share view is restricted to the 2000–2023 window. In snapshot mode the map colors a tract by its share-under-18; in delta mode the map colors by percentage-point change (e.g. a tract that went from 25% to 20% shows as −5 pp, not −20%). Tracts with fewer than 50 children or fewer than 200 people total are masked.

Change calculation. The map colors each tract by percent change in density between the "from" and "to" year. The ranked "biggest gainers" and "biggest losers" lists, however, use absolute change in child count (kids added or lost) because percent change is unstable on small bases — a tract that went from 5 children to 500 is a +9,900% swing but not necessarily a bigger story than a neighborhood that added 20,000 children. The ranked lists also aggregate all tracts within a neighborhood (NYC Planning NTA, or TIGER place outside NYC) so the number reported is the true neighborhood-wide change, not a single cherry-picked tract inside it. Neighborhoods with fewer than 500 children at both endpoints are excluded. Tracts with no neighborhood match (typically large parks or unincorporated fragments at county edges) are excluded from the rankings but still appear on the map.

Tracts built from nothing. A few tracts genuinely went from near-zero child population to substantial — Battery Park City and Hudson Yards (landfill that didn't exist as residential land in 1970), Tribeca and Long Island City-Hunters Point (former industrial waterfront converted to residential), Co-op City and Starrett City (large housing complexes that opened in the early 1970s). These show as an amber color on the delta map rather than a percent-change red, because a percent calculation against a near-zero baseline is meaningless even when the underlying story is real. Criterion: fewer than 50 children in the "from" year, at least 300 in the "to" year.

Masking low-count tracts. Tracts with fewer than 50 children in both the "from" and "to" year (that aren't captured by the "built from nothing" rule above) are drawn in neutral gray rather than an extreme color. Without this mask the map is dominated by parks, cemeteries, and institutional sites (Rikers Island, Prospect Park, Green-Wood Cemetery, Brooklyn Navy Yard) where the AREALM clip didn't fully remove the polygon and the residual sliver would otherwise show "−100%". Totals and ranked lists are unaffected; only the map color is masked.

Caveats. (1) The area-weighted crosswalk assumes uniform population density within each historical tract. Where a 1970 tract was split along a density boundary (e.g., one half a housing project, the other half a park), the split gets an even allocation rather than a population-aware one. (2) ACS 5-year estimates carry margins of error at the tract level; the ranked lists should be read as order-of-magnitude, not precise. (3) Tract GEOIDs for ACS endyears 2020 through 2023 use 2020 boundaries; where a 2020 GEOID differs from its 2010 counterpart the ACS value joins the 2010 tract by exact string match and non-matching tracts hold their 2019 values. (4) The parks/cemeteries/landmarks clip relies on TIGER AREALM, which is incomplete in urban areas — many NYC parks and most NYC cemeteries are not in it. The low-count mask (above) compensates.

National comparison. The 69.7 million figure for U.S. under-18 population in 1970 is from the 1970 decennial census (table P-1, "Persons by age"). The 73.1 million figure for 2023 is from the Census Bureau's Vintage 2023 Population Estimates (national age/sex table NC-EST2023-AGESEX). National under-18 population peaked in 1970 at about 69.7M, fell to a low of about 63.6M in 1984 as the baby boom aged out, then climbed back to today's level on the strength of millennial and Gen Alpha cohorts.

Sources. U.S. Census Bureau via api.census.gov. IPUMS NHGIS, University of Minnesota: Schroeder, J., Van Riper, D., Manson, S., et al. IPUMS National Historical Geographic Information System, version 20.0. Minneapolis: IPUMS. 2025. doi.org/10.18128/D050.V20.0. Source code: github.com/joshgreenman1973/nyc-child-density.