How many John Brennan census records do you have?

We have 9245 US Census records for John Brennan, from 1900 to 1950, across 48 states and DC.

What's in a John Brennan 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 Brennan'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 Brennan census records free?

Yes. All John Brennan 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 Brennan?

We have John Brennan records from the 1900 through 1950 US Federal Census, across 48 states and DC. Use the year and state filters to narrow your results.

How do I find John Brennan 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 Brennan?

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 Brennan — US Census Records & Model Tree

We found 9245 free census records for John Brennan across 6 census years (1900–1950), in 48 states and DC and 725 counties. Each record includes our Model Tree — the same person linked across decades using machine learning, with per-link confidence scores.

John Brennan Census Records by State & County

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Showing of 9245 records for John Brennan US Census, ranked by Model Tree richness

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Year	Name	Age	Location	Birthplace	Occupation	Relation
1930	John L Brennan		Providence, Rhode Island	Rhode Island	Plumber	Head
1940	John Brennan	21	Schuylkill-County, Pennsylvania	Pennsylvania	Laborer	Son
1940	John Brennan	27	Northumberland-County, Pennsylvania	Pennsylvania	Laborer	Son
1940	John Brennan	23	Luzerne-County, Pennsylvania	Pennsylvania	Waiter	Son
1920	John Brennan		Luzerne, Pennsylvania	Wales	Miner	Head
1940	John Brennan	26	Luzerne-County, Pennsylvania	Pennsylvania	Masseur	Head
1920	John J. Brennan		Strafford, New Hampshire	New Hampshire	Electrician	Son
1940	John Brennan	24	Orleans-County, Louisiana	Louisiana	Clerk	Son
1940	John Brennan	22	Allegheny-County, Pennsylvania	Pennsylvania	Helper	Son
1940	John Brennan	42	San-Francisco-County, California	Nebraska	Truck Driver	Son
1940	John Brennan	68	New-York-County, New York	Ireland	Mechanic	Head
1930	John J. Brennan		New York, New York	New York	Secretary	Head
1940	John Brennan	49	Hudson-County, New Jersey	Rhode Island	—	Head
1940	John Brennan	47	Providence-County, Rhode Island	Connecticut	Ass'T Foreman	Head
1920	John Brennan		New York, New York	Ireland	Repairman	Head
1940	John M. Brennan	72	Dakota-County, Minnesota	Minnesota	Farmer	Head
1920	John Brennan		Clearfield, Pennsylvania	Wales	Miner	Head
1940	John Brennan	28	Philadelphia-County, Pennsylvania	Pennsylvania	Supervisor	Head
1940	John J. Brennan	49	Wayne-County, Michigan	Connecticut	Electrician	Head
1940	John D Brennan	48	New-Haven-County, Connecticut	Connecticut	Policeman	Head
1930	John Brennan		Kings, New York	Ireland	Inspector	Head
1930	John Brennan		Cook, Illinois	Ireland	Laborer	Head
1920	John Brennan		Kings, New York	New York	None	Son
1940	John Brennan	16	Benton-County, Minnesota	Minnesota	—	Son
1930	John Brennan		Schuylkill, Pennsylvania	Pennsylvania	Miner	Head
1910	John J. Brennan		Philadelphia, Pennsylvania	England	Plasterer	Head
1930	John Brennan		Montgomery, Pennsylvania	Irish Free State	Watchman	Head
1940	John A. Brennan	40	Suffolk-County, Massachusetts	Massachusetts	Laborer	Head
1930	John Brennan		Montgomery, Pennsylvania	Pennsylvania	Draftsman	Son
1920	John Brennan		Essex, New Jersey	New Jersey	—	Son

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About John Brennan US Census Records & Model Tree

We've indexed 9245 free, proprietary US Census records for John Brennan across 1900–1950, covering 48 states and DC: Alabama, Arizona, Arkansas, California, Colorado, Connecticut, Delaware, District of Columbia, Florida, Georgia, 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, 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 9245 US Census records for John Brennan, from 1900 to 1950, across 48 states and DC.
: 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 Brennan'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 Brennan 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 Brennan records from the 1900 through 1950 US Federal Census, across 48 states and DC. 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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