Middlesex County, MA Population by Age

The median age in Middlesex County, MA is 38.9, as per 2019-2023 ACS 5 -Year Estimates. Of the total population, 16.11% were under the age of 15, 20.63% aged 15 to 29, 47.27% aged 30 to 64, 13.92% aged 65 to 84, and 2.07% were 85 years of age and older.
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Updated Feb 22, 2025

Middlesex County, MA population age distributions

A complete breakdown of Middlesex County's age demographics from 0 to 85 years, distributed across 18 age groups is listed in the table below.

Age Group Population % of Total Population
Under 5 years 82,549 5.09%
5 to 9 years 87,210 5.37%
10 to 14 years 91,682 5.65%
15 to 19 years 102,812 6.34%
20 to 24 years 109,625 6.75%
25 to 29 years 122,364 7.54%
30 to 34 years 122,809 7.57%
35 to 39 years 117,314 7.23%
40 to 44 years 106,993 6.59%
45 to 49 years 101,220 6.24%
50 to 54 years 106,889 6.59%
55 to 59 years 110,747 6.82%
60 to 64 years 101,092 6.23%
65 to 69 years 83,248 5.13%
70 to 74 years 67,899 4.18%
75 to 79 years 45,332 2.79%
80 to 84 years 29,518 1.82%
85 years and over 33,593 2.07%
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Middlesex County, MA population by age group

Key stats
473,878
Population under 25 years
469,480
Population aged 25-44
419,948
Population aged 45-64
259,590
Population aged 65+

Sources: U.S. Census Bureau, American Community Survey (ACS) 2019-2023

FIGURE 1

Middlesex County, MA population by age group.

The largest age group is 30 to 34 years with a population of 122,809 (7.57% of the total population).

Source: U.S. Census Bureau American Community Survey (ACS) 2019-2023 5-Year Estimates.

The largest age group in Middlesex County, MA was for the group of age 30 to 34 years with a population of 122,809 (7.57%), according to the 2019-2023 American Community Survey.

At the same time, the smallest age group in Middlesex County, MA was the 80 to 84 years with a population of 29,518 (1.82%).

Middlesex County, MA population by age cohort

To better understand the age distribution of Middlesex County, MA's population, we divided it into the following 3 cohorts:

  • Children : Under the age of 18 years
  • Adults (working population): Between the age of 18 and 64 years
  • Seniors: 65 years and above

FIGURE 2

Middlesex County, MA population by age cohort

The largest age group was 18 to 64 years with a population of 1.04 million (64.38% of the total population).

Source: U.S. Census Bureau American Community Survey (ACS) 2019-2023 5-Year Estimates.

Middlesex County, MA population by age cohort

Here's the population for each of the three cohorts.

Age Group Population % of Total Population
Under 18 years 318,468 19.62%
18 to 64 years 1,044,838 64.38%
65 years and over 259,590 16%
Exploring Middlesex County's Diversity? Request Customized Data Now!

Key stats for each age cohort as per our analysis of U.S. Census Bureau American Community Survey:

  • Middlesex County 's population under 18 was 19.62%, compared to the 22.16% nationwide.
  • Middlesex County's working population (between 18 and 64) was 64.38%, compared to 61% nationwide.
  • Middlesex County's elderly or the senior population (over 65 age) was 16% as compared to 16.84% nationwide.

Middlesex County, MA population pyramid

Population pyramid for Middlesex County, MA is charted below using the estimates from U.S. Census Bureau's American Community Survey 5-Year estimates. A wide base suggests population increase, narrow base indicates declining birth rates.

Key stats from our analysis of the Middlesex County's population pyramid:

  • Youth dependency ratio, which is the number of children aged 0-14 per 100 persons aged 15-64, for Middlesex County, MA, is 23.7.
  • Old-age dependency ratio, which is the number of persons aged 65 or over per 100 persons aged 15-64, for Middlesex County, MA, is 23.6.
  • Total dependency ratio for Middlesex County, MA is 47.3.
  • Potential support ratio, which is the number of youth (working age population) per elderly, for Middlesex County, MA is 4.2.

FIGURE 3

Middlesex County, MA population pyramid

Middlesex County population distrubution across age and gender. A wide base suggests population increase, narrow base indicates declining birth rates.

Source: U.S. Census Bureau American Community Survey (ACS) 2019-2023 5-Year Estimates.

Middlesex County, MA population pyramid

Here's the Middlesex County, MA's male and female population across different age groups .

Age Group Population(Male) Population(Female) Total Population
Under 5 years 42,280 40,269 82,549
5 to 9 years 45,457 41,753 87,210
10 to 14 years 46,140 45,542 91,682
15 to 19 years 52,397 50,415 102,812
20 to 24 years 55,070 54,555 109,625
25 to 29 years 62,653 59,711 122,364
30 to 34 years 62,373 60,436 122,809
35 to 39 years 58,353 58,961 117,314
40 to 44 years 53,898 53,095 106,993
45 to 49 years 50,399 50,821 101,220
50 to 54 years 52,939 53,950 106,889
55 to 59 years 56,225 54,522 110,747
60 to 64 years 48,169 52,923 101,092
65 to 69 years 40,303 42,945 83,248
70 to 74 years 30,464 37,435 67,899
75 to 79 years 19,464 25,868 45,332
80 to 84 years 12,516 17,002 29,518
85 years and over 11,813 21,780 33,593
Exploring Middlesex County's Diversity? Request Customized Data Now!

Things to know

What is the population of Middlesex County, MA under 18?

Middlesex County's population under the age of 18 is 318,468, as per the latest U.S. Census Bureau's American Community Survey estimates. This population is 19.62% of the total resident population of Middlesex County, MA.

What is the aging population in Middlesex County, MA?

Middlesex County's population aged 65 years and above was 259,590. As per the U.S. Census Bureau's American Community Survey, this population is 16% of the entire population.

References

Datasets

Explore datasets by year of publication.
2025
Middlesex County, MA Age Group Population Dataset: A Complete Breakdown of Middlesex County Age Demographics from 0 to 85 Years and Over, Distributed Across 18 Age Groups // 2025 Edition
Last updated February 22, 2025
ACS
Free
Neilsberg
CSV, JSON
2019-2023
CC BY 4.0
About this dataset

Context

The dataset tabulates the Middlesex County population distribution across 18 age groups. It lists the population in each age group along with the percentage population relative of the total population for Middlesex County. The dataset can be utilized to understand the population distribution of Middlesex County by age. For example, using this dataset, we can identify the largest age group in Middlesex County.

Key observations

The largest age group in Middlesex County, MA was for the group of age 30 to 34 years years with a population of 122,809 (7.57%), according to the ACS 2019-2023 5-Year Estimates. At the same time, the smallest age group in Middlesex County, MA was the 80 to 84 years years with a population of 29,518 (1.82%). Source: U.S. Census Bureau American Community Survey (ACS) 2019-2023 5-Year Estimates

Content

When available, the data consists of estimates from the U.S. Census Bureau American Community Survey (ACS) 2019-2023 5-Year Estimates

Age groups:

  • Under 5 years
  • 5 to 9 years
  • 10 to 14 years
  • 15 to 19 years
  • 20 to 24 years
  • 25 to 29 years
  • 30 to 34 years
  • 35 to 39 years
  • 40 to 44 years
  • 45 to 49 years
  • 50 to 54 years
  • 55 to 59 years
  • 60 to 64 years
  • 65 to 69 years
  • 70 to 74 years
  • 75 to 79 years
  • 80 to 84 years
  • 85 years and over

Variables / Data Columns

  • Age Group: This column displays the age group in consideration
  • Population: The population for the specific age group in the Middlesex County is shown in this column.
  • % of Total Population: This column displays the population of each age group as a proportion of Middlesex County total population. Please note that the sum of all percentages may not equal one due to rounding of values.

Good to know

Margin of Error

Data in the dataset are based on the estimates and are subject to sampling variability and thus a margin of error. Neilsberg Research recommends using caution when presening these estimates in your research.

Custom data

If you do need custom data for any of your research project, report or presentation, you can contact our research staff at research@neilsberg.com for a feasibility of a custom tabulation on a fee-for-service basis.

Inspiration

Neilsberg Research Team curates, analyze and publishes demographics and economic data from a variety of public and proprietary sources, each of which often includes multiple surveys and programs. The large majority of Neilsberg Research aggregated datasets and insights is made available for free download at https://www.neilsberg.com/research/.

Recommended for further research

This dataset is a part of the main dataset for Middlesex County Population by Age. You can refer the same here

Middlesex County, MA Age Cohorts Dataset: Children, Working Adults, and Seniors in Middlesex County - Population and Percentage Analysis // 2025 Edition
Last updated February 22, 2025
ACS
Free
Neilsberg
CSV, JSON
2019-2023
CC BY 4.0
About this dataset

Context

The dataset tabulates the Middlesex County population by age cohorts (Children: Under 18 years; Working population: 18-64 years; Senior population: 65 years or more). It lists the population in each age cohort group along with its percentage relative to the total population of Middlesex County. The dataset can be utilized to understand the population distribution across children, working population and senior population for dependency ratio, housing requirements, ageing, migration patterns etc.

Key observations

The largest age group was 18 to 64 years with a poulation of 1.04 million (64.38% of the total population). Source: U.S. Census Bureau American Community Survey (ACS) 2019-2023 5-Year Estimates.

Content

When available, the data consists of estimates from the U.S. Census Bureau American Community Survey (ACS) 2019-2023 5-Year Estimates.

Age cohorts:

  • Under 18 years
  • 18 to 64 years
  • 65 years and over

Variables / Data Columns

  • Age Group: This column displays the age cohort for the Middlesex County population analysis. Total expected values are 3 groups ( Children, Working Population and Senior Population).
  • Population: The population for the age cohort in Middlesex County is shown in the following column.
  • Percent of Total Population: The population as a percent of total population of the Middlesex County is shown in the following column.

Good to know

Margin of Error

Data in the dataset are based on the estimates and are subject to sampling variability and thus a margin of error. Neilsberg Research recommends using caution when presening these estimates in your research.

Custom data

If you do need custom data for any of your research project, report or presentation, you can contact our research staff at research@neilsberg.com for a feasibility of a custom tabulation on a fee-for-service basis.

Inspiration

Neilsberg Research Team curates, analyze and publishes demographics and economic data from a variety of public and proprietary sources, each of which often includes multiple surveys and programs. The large majority of Neilsberg Research aggregated datasets and insights is made available for free download at https://www.neilsberg.com/research/.

Recommended for further research

This dataset is a part of the main dataset for Middlesex County Population by Age. You can refer the same here

Middlesex County, MA Population Pyramid Dataset: Age Groups, Male and Female Population, and Total Population for Demographics Analysis // 2025 Edition
Last updated February 22, 2025
ACS
Free
Neilsberg
CSV, JSON
2019-2023
CC BY 4.0
About this dataset

Context

The dataset tabulates the data for the Middlesex County, MA population pyramid, which represents the Middlesex County population distribution across age and gender, using estimates from the U.S. Census Bureau American Community Survey (ACS) 2019-2023 5-Year Estimates. It lists the male and female population for each age group, along with the total population for those age groups. Higher numbers at the bottom of the table suggest population growth, whereas higher numbers at the top indicate declining birth rates. Furthermore, the dataset can be utilized to understand the youth dependency ratio, old-age dependency ratio, total dependency ratio, and potential support ratio.

Key observations

  • Youth dependency ratio, which is the number of children aged 0-14 per 100 persons aged 15-64, for Middlesex County, MA, is 23.7.
  • Old-age dependency ratio, which is the number of persons aged 65 or over per 100 persons aged 15-64, for Middlesex County, MA, is 23.6.
  • Total dependency ratio for Middlesex County, MA is 47.3.
  • Potential support ratio, which is the number of youth (working age population) per elderly, for Middlesex County, MA is 4.2.
Content

When available, the data consists of estimates from the U.S. Census Bureau American Community Survey (ACS) 2019-2023 5-Year Estimates.

Age groups:

  • Under 5 years
  • 5 to 9 years
  • 10 to 14 years
  • 15 to 19 years
  • 20 to 24 years
  • 25 to 29 years
  • 30 to 34 years
  • 35 to 39 years
  • 40 to 44 years
  • 45 to 49 years
  • 50 to 54 years
  • 55 to 59 years
  • 60 to 64 years
  • 65 to 69 years
  • 70 to 74 years
  • 75 to 79 years
  • 80 to 84 years
  • 85 years and over

Variables / Data Columns

  • Age Group: This column displays the age group for the Middlesex County population analysis. Total expected values are 18 and are define above in the age groups section.
  • Population (Male): The male population in the Middlesex County for the selected age group is shown in the following column.
  • Population (Female): The female population in the Middlesex County for the selected age group is shown in the following column.
  • Total Population: The total population of the Middlesex County for the selected age group is shown in the following column.

Good to know

Margin of Error

Data in the dataset are based on the estimates and are subject to sampling variability and thus a margin of error. Neilsberg Research recommends using caution when presening these estimates in your research.

Custom data

If you do need custom data for any of your research project, report or presentation, you can contact our research staff at research@neilsberg.com for a feasibility of a custom tabulation on a fee-for-service basis.

Inspiration

Neilsberg Research Team curates, analyze and publishes demographics and economic data from a variety of public and proprietary sources, each of which often includes multiple surveys and programs. The large majority of Neilsberg Research aggregated datasets and insights is made available for free download at https://www.neilsberg.com/research/.

Recommended for further research

This dataset is a part of the main dataset for Middlesex County Population by Age. You can refer the same here

If you're looking for datasets from another year, please feel free to contact us at research@neilsberg.com and we'll be happy to assist you further.

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Neilsberg Research
Neilsberg Research team are data scientists with expertise in processing, analysis and visualization of big data helping small businesses make right decisions.

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