How many John Mcmahon census records do you have?

We have 7959 US Census records for John Mcmahon, from 1900 to 1950, across 50 states and DC.

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

Yes. All John 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 John Mcmahon?

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

How do I find John 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 John 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.

John Mcmahon — US Census Records & Model Tree

We found 7959 free census records for John Mcmahon across 6 census years (1900–1950), in 50 states and DC and 853 counties. Each record includes our Model Tree — the same person linked across decades using machine learning, with per-link confidence scores.

John Mcmahon Census Records by State & County

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Showing of 7959 records for John Mcmahon US Census, ranked by Model Tree richness

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Year	Name	Age	Location	Birthplace	Occupation	Relation
1940	John X Mcmahon	54	Essex-County, New York	Colorado	Farmer	Son
1930	John F. Mcmahon		Middlesex, Massachusetts	Massachusetts	Clerk	Son
1920	John H Mcmahon		Merrimack, New Hampshire	New Hampshire	Salesman	Son
1930	John Mcmahon		Kings, New York	New York	Salesman	Son
1920	John Mcmahon		King, Washington	Washington	—	Son
1940	John Jr. Mcmahon	21	St.-Louis-City-County, Missouri	Missouri	Tinner & Mechanic	Son
1940	John Mcmahon	21	Suffolk-County, Massachusetts	Massachusetts	Salesman	Head
1930	John Mcmahon		Rensselaer, New York	New York	Typewriter	Head
1930	John W Mcmahon		Coffee, Tennessee	Tennessee	Farmer	Head
1940	John Mcmahon	43	Bronx-County, New York	Ireland	Laborer	Head
1920	John Mcmahon		Middlesex, Massachusetts	Ireland	Fireman	Head
1940	John Mcmahon	70	Kings-County, New York	Ireland	Watchman	Head
1940	John Mcmahon	54	St.-Louis-City-County, Missouri	Missouri	House Painter	Head
1940	John E Mcmahon	52	Ramsey-County, Minnesota	Wisconsin	Purchasing Agent	Head
1920	John Mcmahon		New York, New York	Ireland	—	Head
1930	John Mcmahon		Hamilton, Illinois	Illinois	Farmer	Head
1940	John Mcmahon	38	Okanogan-County, Washington	Montana	Carpenter Foreman	Head
1940	John Mcmahon	72	New-York-County, New York	SCOTLAND	Grocery-Man	Head
1920	John Mcmahon		New York, New York	Ireland	Foreman	Head
1930	John P. Mcmahon		Lucas, Ohio	Ohio	Foreman	Head
1940	John J. Mcmahon	57	Bronx-County, New York	Ireland	Superintendent	Head
1930	John H Mcmahon		Suffolk, Massachusetts	Massachusetts	Sheet Metal Worker	Head
1930	John Mcmahon		Seminole, Florida	Florida	—	Son
1930	John Mcmahon		Kings, New York	New York	Messenger	Son
1910	John Mcmahon		Essex, New Jersey	New York	—	Son
1940	John M. Mcmahon	24	Suffolk-County, Massachusetts	Massachusetts	Retail Grocery Meat Clerk	Son
1940	John M. Mcmahon	14	Middlesex-County, Massachusetts	Massachusetts	—	Son
1920	John Mcmahon		Erie, New York	New York	None	Son
1930	John Mcmahon		Kings, New York	New York	Runner	Son
1930	John S. Mcmahon		Knox, Tennessee	Tennessee	—	Son

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About John Mcmahon US Census Records & Model Tree

We've indexed 7959 free, proprietary US Census records for John Mcmahon across 1900–1950, covering 50 states and DC: 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, 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 7959 US Census records for John Mcmahon, from 1900 to 1950, across 50 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 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 John 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 John Mcmahon records from the 1900 through 1950 US Federal Census, across 50 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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