How many John Monahan census records do you have?

We have 4265 US Census records for John Monahan, from 1900 to 1950, across 50 states, DC, and 1 territory.

What's in a John Monahan census record?

You'll see John's age, birthplace, occupation, and relationship to the head of household — plus everyone else who lived in the same home. For 1940 and 1950 records, you can also view the original handwritten census page.

How do I use census records for family research?

Census records are a snapshot of a family every 10 years. You can follow John Monahan's household over time — see when children appear, when people move states, and who's living together. YourRoots connects census data with Tree Matching and AI tools so you can build out your tree faster.

Are John Monahan census records free?

Yes. All John Monahan census records on YourRoots are free to search and view — no subscription required. We built our own index from the original federal census images.

Which census years and states cover John Monahan?

We have John Monahan records from the 1900 through 1950 US Federal Census, across 50 states, DC, and 1 territory. Use the year and state filters to narrow your results.

How do I find John Monahan in the census?

Start by narrowing the year and state. If you know an approximate birth year, use the age column to match — census age minus the census year gives you a birth year estimate. Household members, birthplace, and occupation help confirm you have the right person.

What is the Model Tree for John Monahan?

The Model Tree is YourRoots' unique feature that links a person across multiple census decades and reconstructs their likely family — parents, siblings, spouse, and children — based on household patterns. It turns isolated records into a connected family network.

Where does the census data come from?

All records originate from the US Federal Census microfilm digitized by NARA (National Archives and Records Administration). YourRoots re-indexed the original page images using modern AI, catching names and details that older transcriptions missed.

John Monahan — US Census Records & Model Tree

We found 4265 free census records for John Monahan across 6 census years (1900–1950), in 50 states, DC, and 1 territory and 496 counties. Each record includes our Model Tree — the same person linked across decades using machine learning, with per-link confidence scores.

John Monahan Census Records by State & County

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Showing of 4265 records for John Monahan US Census, ranked by Model Tree richness

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Year	Name	Age	Location	Birthplace	Occupation	Relation
1940	John Monahan	25	Hamilton-County, Ohio	Ohio	Office Clerk	Son
1940	John Monahan	23	Kings-County, New York	New York	Helper	Son
1940	John Monahan	31	Middlesex-County, Massachusetts	Massachusetts	Shipping Clerk	Son
1940	John Jr. Monahan	25	Passaic-County, New Jersey	New Jersey	Bookkeeper	Son
1940	John Monahan	32	New-York-County, New York	New York	Elevator Operator	Head
1940	John J. Monahan	74	Suffolk-County, Massachusetts	New Jersey	Retired	Head
1920	John Monahan		Allegheny, Pennsylvania	Ireland	Retired	Head
1940	John Monahan	61	Berrien-County, Michigan	New York	Plumber	Head
1940	John Monahan	60	Suffolk-County, Massachusetts	Vermont	Trainman	Head
1940	John Monahan	54	Kings-County, New York	Ireland	Longshoreman	Head
1940	John (X) Monahan	70	Rensselaer-County, New York	England	Street Sweeper	Head
1940	John Monahan	20	New-York-County, New York	New York	Grocery Boy	Son
1940	John P. Monahan	19	Fayette-County, Pennsylvania	Pennsylvania	—	Son
1900	John Monahan	42	Northumberland, Pennsylvania	New York	Attorney	Head
1940	John Jr. Monahan	25	Philadelphia-County, Pennsylvania	Pennsylvania	Clerk	Son
1930	John Monahan		Essex, Massachusetts	Ireland	Plumber Helper	Head
1940	John A Monahan	10	Suffolk-County, Massachusetts	Massachusetts	—	Son
1910	John J Monahan		Schuylkill, Pennsylvania	England	Superintendent	Head
1930	John Jr. Monahan		Union, New Jersey	New Jersey	Instructor	Son
1940	John H. Monahan	22	Worcester-County, Massachusetts	Massachusetts	Machine Operator	Son
1940	John B. Monahan	28	Suffolk-County, Massachusetts	Massachusetts	Clerk	Son
1940	John L. Monahan	44	Deer-Lodge-County, Montana	Montana	Custodian	Head
1940	John Monahan	56	Worcester-County, Massachusetts	Massachusetts	Storekeeper	Head
1910	John Monahan		Norfolk, Massachusetts	Ireland	Iceman	Head
1940	John Monahan	14	New-York-County, New York	New York	—	Son
1940	John Monahan	27	Norfolk-County, Massachusetts	Massachusetts	Chiropractor	Son
1910	John Monahan		Kings, New York	Rhode Island	Conductor	Head
1940	John Monahan	16	Kings-County, New York	Brooklyn	—	Son
1930	John M Jr Monahan		Hamilton, Ohio	Ohio	Grinder	Son
1910	John Monahan		Fairfield, Connecticut	Ireland	Laborer	Head

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About John Monahan US Census Records & Model Tree

We've indexed 4265 free, proprietary US Census records for John Monahan across 1900–1950, covering 50 states, DC, and 1 territory: Alabama, Alaska, Arizona, Arkansas, California, Colorado, Connecticut, Delaware, District of Columbia, Florida, Georgia, Hawaii, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Maryland, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, Nevada, New Hampshire, New Jersey, New Mexico, New York, North Carolina, North Dakota, Ohio, Oklahoma, Oregon, Pennsylvania, Puerto Rico, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Utah, Vermont, Virginia, Washington, West Virginia, Wisconsin, Wyoming.

Each record includes our Model Tree — a longitudinal reconstruction that links the same person across census decades using machine learning (XGBoost record linkage). Every link carries a confidence score: Verified (≥0.99), Confirmed (≥0.95), or Linked (lower confidence). This tells you not just what the census says, but how reliably we've connected records across time.

Every record also shows the full household — who John lived with, their ages, birthplaces, and occupations. For 1940 and 1950 records, you can view the original handwritten census page from the National Archives.

How we build the Model Tree. YourRoots independently indexes US Census records from NARA microfilm and links persons across decades using XGBoost-based record linkage. Each link's confidence is a per-pair match score from the model. Household corroboration (co-residents appearing on the same census pages in multiple years) strengthens the signal. The Model Tree is not a family tree submitted by users — it's reconstructed from the census data itself.

Last updated: July 30, 2026

Frequently Asked Questions

: We have 4265 US Census records for John Monahan, from 1900 to 1950, across 50 states, DC, and 1 territory.
: You'll see John's age, birthplace, occupation, and relationship to the head of household — plus everyone else who lived in the same home. For 1940 and 1950 records, you can also view the original handwritten census page.
: Census records are a snapshot of a family every 10 years. You can follow John Monahan's household over time — see when children appear, when people move states, and who's living together. YourRoots connects census data with Tree Matching and AI tools so you can build out your tree faster.
: Yes. All John Monahan census records on YourRoots are free to search and view — no subscription required. We built our own index from the original federal census images.
: We have John Monahan records from the 1900 through 1950 US Federal Census, across 50 states, DC, and 1 territory. Use the year and state filters above to narrow your results.
: Start by narrowing the year and state. If you know an approximate birth year, use the age column to match — census age minus the census year gives you a birth year estimate. Household members, birthplace, and occupation help confirm you have the right person.
: The Model Tree is YourRoots' unique feature that links a person across multiple census decades and reconstructs their likely family — parents, siblings, spouse, and children — based on household patterns. It turns isolated records into a connected family network.
: All records originate from the US Federal Census microfilm digitized by NARA (National Archives and Records Administration). YourRoots re-indexed the original page images using modern AI, catching names and details that older transcriptions missed.

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