How many William Mcmahon census records do you have?

We have 3534 US Census records for William Mcmahon, from 1900 to 1950, across 48 states and DC.

What's in a William Mcmahon census record?

You'll see William'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 William Mcmahon'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 William Mcmahon census records free?

Yes. All William Mcmahon 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 William Mcmahon?

We have William Mcmahon 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 William Mcmahon 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 William Mcmahon?

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.

William Mcmahon — US Census Records & Model Tree

We found 3534 free census records for William Mcmahon across 6 census years (1900–1950), in 48 states and DC and 612 counties. Each record includes our Model Tree — the same person linked across decades using machine learning, with per-link confidence scores.

William Mcmahon Census Records by State & County

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Showing of 3534 records for William Mcmahon US Census, ranked by Model Tree richness

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Year	Name	Age	Location	Birthplace	Occupation	Relation
1940	William J. Mcmahon	47	Kings-County, New York	New York	Policeman	Head
1920	William Mcmahon		Ontario, New York	New York	Farmer	Head
1930	William C Mcmahon		Logan, Oklahoma	Tennessee	Farmer	Head
1930	William A. Mcmahon		Lane, Oregon	Oregon	Laborer	Head
1900	William Mcmahon	36	Merrimack, New Hampshire	Ireland	Car-Inspector	Head
1930	William J. Mcmahon		Cuyahoga, Ohio	Ohio	Fireman	Head
1920	William Mcmahon		Williamson, Tennessee	Tennessee	Farm Laborer	Son
1940	William J. Mcmahon	10	Middlesex-County, Massachusetts	Massachusetts	—	Son
1930	William Mcmahon		Forrest, Mississippi	Alabama	—	Son
1940	William P. Mcmahon	43	Kent-County, Rhode Island	Rhode Island	Policeman	Head
1930	William Mcmahon		Middlesex, Massachusetts	Massachusetts	—	Son
1940	William Mcmahon	12	Erie-County, New York	New York	—	Son
1940	William Mcmahon	10	Hudson-County, New Jersey	New Jersey	—	Son
1940	William Mcmahon	12	Hudson-County, New Jersey	New Jersey	—	Son
1930	William J. Mcmahon		Milwaukee, Wisconsin	Massachusetts	Telegrapher	Head
1940	William Mcmahon	25	Queens-County, New York	New York	Butcher	Son
1910	William Mcmahon		Baxter, Arkansas	Arkansas	—	Son
1920	William Mcmahon		New York, New York	New York	—	Son
1930	William B Mcmahon		Middlesex, Massachusetts	Massachusetts	—	Son
1940	William A Mcmahon	21	Hamilton-County, Ohio	Ohio	Truck Driver	Son
1940	William Mcmahon	55	Delaware-County, Iowa	Iowa	Farmer	Head
1930	William Mcmahon		Lucas, Ohio	Ohio	—	Son
1940	William Mcmahon	17	Cook-County, Illinois	Illinois	—	Son
1940	William J. Mcmahon	27	Suffolk-County, Massachusetts	Scotland	—	Son
1940	William Mcmahon	22	Yancey-County, North Carolina	North Carolina	Cutter	Son
1940	William Mcmahon	12	Cook-County, Illinois	Illinois	—	Son
1930	William J. Mcmahon		Providence, Rhode Island	Rhode Island	Wrapper	Son
1930	William Mcmahon		Hudson, New Jersey	New Jersey	Stoker	Head
1930	William Mcmahon		Hudson, New Jersey	New Jersey	Worker	Son
1930	William Mcmahon		Lucas, Ohio	Ohio	Electrician	Head

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About William Mcmahon US Census Records & Model Tree

We've indexed 3534 free, proprietary US Census records for William Mcmahon across 1900–1950, covering 48 states and DC: Alabama, 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, 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 William 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 3534 US Census records for William Mcmahon, from 1900 to 1950, across 48 states and DC.
: You'll see William'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 William Mcmahon'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 William Mcmahon 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 William Mcmahon 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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