Watertown, Massachusetts demographics

Watertown, MA demographics: median age 39.4; 66.5% of adults 25+ hold a bachelor’s degree. Age, race, households, languages and education, ACS 2020–2024 with margins of error.

ACS 2020–2024 · Watertown city, Massachusetts · Incorporated city · GEOID 2573405. The survey estimates a population of 35,543 for its five-year window. This is separate from the annual July 2025 population estimate on the city overview.

Median age in Watertown is 39.4 years, with a 90% margin of error of 1.3 years. There are 16,371 households (±500). Age and household distributions show how these totals are composed; they do not establish which neighborhood suits a particular person.

Every count and share is an estimate. “±” is a 90% margin of error (MOE); pp means percentage points. Derived shares use the category count divided by the named universe. Aggregated category MOEs and percentage MOEs are approximate. A margin larger than half its estimate is flagged as low precision. Blank source uncertainty is shown as unavailable, never zero.

Age distribution and sex

City, state and U.S. estimates · ACS 2020–2024
Measure / survey universe	City estimate ± MOE	State estimate ± MOE	U.S. estimate ± MOE
Median age Total population · years	39.4 ±1.3	40.0 ±0.1	38.9 ±0.1

Age groups · B01001 · ACS 2020–2024 Total population: 35,543
Category	Count ± MOE	Share ± MOE (pp)	Massachusetts	U.S.
Under 18	5,066 ±551	14.3% ±1.6 pp	19.4%	22.0%
18–34	9,620 ±793	27.1% ±2.2 pp	23.9%	22.8%
35–64	14,351 ±931	40.4% ±2.6 pp	38.9%	38.0%
65 and older	6,506 ±632	18.3% ±1.8 pp	17.9%	17.2%

Sex categories as published by ACS · B01001 · ACS 2020–2024 Total population: 35,543
Category	Count ± MOE	Share ± MOE (pp)	Massachusetts	U.S.
Male	16,179 ±599	45.5% ±1.7 pp	48.9%	49.5%
Female	19,364 ±602	54.5% ±1.7 pp	51.1%	50.5%

The age groups are mutually exclusive and cover the entire population. The sex categories follow this ACS table’s published classification; they are not a survey of gender identity.

Race and Hispanic origin

Race · B02001 · ACS 2020–2024 Total population: 35,543
Category	Count ± MOE	Share ± MOE (pp)	Massachusetts	U.S.
White alone	25,339 ±1,082	71.3% ±3.0 pp	68.6%	61.0%
Black or African American alone	1,344 ±501	3.8% ±1.4 pp	6.8%	12.2%
American Indian and Alaska Native alone	52 ±72 · low precision	0.1% ±0.2 pp · low precision	0.2%	0.9%
Asian alone	4,150 ±763	11.7% ±2.1 pp	7.3%	6.0%
Native Hawaiian and Other Pacific Islander alone	0 ±29 · low precision	0.0% ±0.1 pp · low precision	0.0%	0.2%
Some other race alone	1,399 ±492	3.9% ±1.4 pp	5.8%	7.1%
Two or more races	3,259 ±683	9.2% ±1.9 pp	11.1%	12.6%

Hispanic or Latino origin · B03003 · ACS 2020–2024 Total population: 35,543
Category	Count ± MOE	Share ± MOE (pp)	Massachusetts	U.S.
Not Hispanic or Latino	33,403 ±555	94.0% ±1.6 pp	86.7%	80.7%
Hispanic or Latino	2,140 ±553	6.0% ±1.6 pp	13.3%	19.3%

Hispanic origin and race are separate questions. People of Hispanic or Latino origin may be of any race and appear in both tables. Do not add the Hispanic share to race shares. Race alone and two-or-more-race groups are the mutually exclusive categories of the race table.

Household types, children and living alone

Household types · B11001 · ACS 2020–2024 Households: 16,371
Category	Count ± MOE	Share ± MOE (pp)	Massachusetts	U.S.
Married-couple family	6,642 ±488	40.6% ±2.7 pp	45.9%	46.9%
Other family: male householder, no spouse present	469 ±179	2.9% ±1.1 pp	4.7%	5.1%
Other family: female householder, no spouse present	1,692 ±394	10.3% ±2.4 pp	11.9%	12.2%
Nonfamily: householder living alone	5,584 ±601	34.1% ±3.5 pp	28.8%	28.7%
Nonfamily: householder not living alone	1,984 ±379	12.1% ±2.3 pp	8.9%	7.0%

Households with children · B11005 · ACS 2020–2024 Households: 16,371
Category	Count ± MOE	Share ± MOE (pp)	Massachusetts	U.S.
Households with people under 18	3,276 ±317	20.0% ±1.8 pp	27.9%	29.5%
Households without people under 18	13,095 ±673	80.0% ±3.3 pp	72.1%	70.5%

Household size · B11016 · ACS 2020–2024 Households: 16,371
Category	Count ± MOE	Share ± MOE (pp)	Massachusetts	U.S.
One-person nonfamily households	5,584 ±601	34.1% ±3.5 pp	28.8%	28.7%
Two-person households	6,011 ±659	36.7% ±3.9 pp	33.3%	33.8%
Three-person households	2,559 ±390	15.6% ±2.3 pp	16.5%	15.3%
Four-person households	1,573 ±275	9.6% ±1.7 pp	13.5%	12.6%
Five-person households	329 ±114	2.0% ±0.7 pp	5.2%	5.9%
Six-person households	244 ±108	1.5% ±0.7 pp	1.8%	2.2%
Seven or more people	71 ±57 · low precision	0.4% ±0.3 pp · low precision	0.9%	1.4%

A family household contains related people under the Census definition. A nonfamily household can contain one person or unrelated people sharing a home. Households with children can also appear in the household-type and size tables, so those tables must not be added together. Household estimates exclude people living in group quarters from the household universe.

Nativity and languages spoken at home

Nativity · B05002 · ACS 2020–2024 Total population: 35,543
Category	Count ± MOE	Share ± MOE (pp)	Massachusetts	U.S.
Native	26,423 ±832	74.3% ±2.3 pp	82.0%	85.9%
Foreign born	9,120 ±834	25.7% ±2.3 pp	18.0%	14.1%

Language spoken at home · C16001 · ACS 2020–2024 Population age 5 and older: 33,854
Category	Count ± MOE	Share ± MOE (pp)	Massachusetts	U.S.
English only	23,604 ±981	69.7% ±2.8 pp	74.9%	77.7%
Spanish	1,579 ±513	4.7% ±1.5 pp	9.7%	13.6%
French, Haitian, or Cajun	412 ±167	1.2% ±0.5 pp	1.9%	0.7%
German or other West Germanic	173 ±95 · low precision	0.5% ±0.3 pp · low precision	0.3%	0.5%
Russian, Polish, or other Slavic	439 ±191	1.3% ±0.6 pp	1.0%	0.7%
Other Indo-European	4,690 ±860	13.9% ±2.5 pp	6.1%	2.0%
Korean	107 ±75 · low precision	0.3% ±0.2 pp · low precision	0.3%	0.3%
Chinese, including Mandarin and Cantonese	944 ±362	2.8% ±1.1 pp	2.2%	1.1%
Vietnamese	27 ±27 · low precision	0.1% ±0.1 pp · low precision	0.7%	0.5%
Tagalog, including Filipino	227 ±224 · low precision	0.7% ±0.7 pp · low precision	0.1%	0.6%
Other Asian and Pacific Island	549 ±237	1.6% ±0.7 pp	1.3%	1.1%
Arabic	726 ±548 · low precision	2.1% ±1.6 pp · low precision	0.6%	0.5%
Other and unspecified	377 ±288 · low precision	1.1% ±0.9 pp · low precision	1.0%	0.8%

Foreign born means not a U.S. citizen at birth; it includes naturalized citizens. Language categories describe speech at home among people age five and older. A language other than English at home does not establish that someone cannot speak English. This city page uses the published C16001 summary categories because the more detailed B16001 table does not provide these city records in this release.

Educational attainment

Highest completed education · B15003 · ACS 2020–2024 Population age 25 and older: 28,445
Category	Count ± MOE	Share ± MOE (pp)	Massachusetts	U.S.
Less than high school graduate	1,398 ±365	4.9% ±1.3 pp	8.6%	10.4%
High school graduate or equivalency	3,898 ±576	13.7% ±2.0 pp	22.6%	26.0%
Some college, no degree	2,654 ±428	9.3% ±1.5 pp	14.1%	19.1%
Associate’s degree	1,571 ±357	5.5% ±1.3 pp	7.5%	8.8%
Bachelor’s degree	8,740 ±698	30.7% ±2.4 pp	25.5%	21.6%
Graduate or professional degree	10,184 ±732	35.8% ±2.5 pp	21.8%	14.1%

The denominator excludes residents under 25. Each person is counted in the highest attainment category they completed. This table does not measure the quality of local schools or the education level of every current student.

Residence one year earlier

Geographic mobility · B07003 · ACS 2020–2024 Population age 1 and older: 35,212
Category	Count ± MOE	Share ± MOE (pp)	Massachusetts	U.S.
Same house	29,552 ±880	83.9% ±2.5 pp	88.3%	87.7%
Moved within same county	3,010 ±558	8.5% ±1.6 pp	5.6%	6.3%
Moved from a different county in the same state	1,196 ±368	3.4% ±1.0 pp	3.0%	3.1%
Moved from a different state	921 ±292	2.6% ±0.8 pp	2.2%	2.3%
Moved from abroad	533 ±419 · low precision	1.5% ±1.2 pp · low precision	0.9%	0.6%

These are respondents’ residence patterns one year before their survey response, pooled across the five-year window. They are not a net migration count for 2025. A person can move to a different house within the same city or county; moves within the same county should not automatically be interpreted as new arrivals to the city.

Health insurance, internet access and veterans

1.3% of Watertown residents (±0.6 percentage points) had no health insurance coverage when surveyed, compared with 2.6% in Massachusetts and 8.4% nationally. 95.1% of households subscribe to broadband of any type, including cellular data plans. A subscription is not the same as available service: the FCC National Broadband Map shows providers at a specific address.

City, state and U.S. shares · ACS 2020–2024
Measure	Watertown	Massachusetts	U.S.	Compared with Massachusetts
People without health insurance Civilian noninstitutionalized population	1.3% ±0.6 pp · low precision	2.6%	8.4%	Lower
Households with a broadband subscription Households	95.1% ±1.3 pp	92.8%	91.0%	Higher
Veterans Civilian population age 18 and older	3.4% ±0.8 pp	4.3%	6.2%	Lower

Reading and reusing the estimates

The Census table links above lead to the original detailed tables. Counts, source universes and uncertainty are retained in the source observation download for Watertown . Compare these figures with the same survey window; do not compare one city’s five-year estimate with another city’s annual estimate as though they measured the same period. For methods, see uncertainty and denominator calculations.

Read Watertown housing and cost context or return to the city profile.