How many John Duffy census records do you have?

We have 8460 US Census records for John Duffy, from 1900 to 1950, across 50 states, DC, and 1 territory.

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

Yes. All John Duffy 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 Duffy?

We have John Duffy 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 Duffy 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 Duffy?

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 Duffy — US Census Records & Model Tree

We found 8460 free census records for John Duffy across 6 census years (1900–1950), in 50 states, DC, and 1 territory and 771 counties. Each record includes our Model Tree — the same person linked across decades using machine learning, with per-link confidence scores.

John Duffy Census Records by State & County

Records per state:

Census Record Search

First Name

Middle Name

Last Name (Required)

Census Year

State

Birth Year

Year Range

Birthplace

Age From

Age To

Exact match: Name Location Year

Alternate First Names (comma-separated)

Alternate Last Names (comma-separated)

County

Sex

Marital Status

Race

Relationship to Head

Occupation

Census Page ID

Family Members (in same household)

Search Records

Showing of 8460 records for John Duffy US Census, ranked by Model Tree richness

No records match your filters.

Year	Name	Age	Location	Birthplace	Occupation	Relation
1940	John E. Duffy	42	Denver-County, Colorado	Colorado	—	Head
1940	John Duffy	45	Kings-County, New York	Scotland	Tinsmith	Head
1930	John J. Jr. Duffy		Charleston, South Carolina	South Carolina	Pharmacist	Son
1930	John G Duffy		Merrimack, New Hampshire	New Hampshire	Laborer	Son
1940	John Duffy	26	Cook-County, Illinois	Illinois	Clerk	Son
1940	John W Duffy	27	San-Francisco-County, California	California	Warehouseman	Son
1940	John Duffy	35	Hudson-County, New Jersey	New Jersey	Checker	Son
1940	John M. Duffy	45	Shelby-County, Indiana	Kentucky	Insurance Agt	Son
1940	John Duffy	73	New-York-County, New York	Ireland	—	Head
1930	John F Duffy		Providence, Rhode Island	Rhode Island	Electrician	Head
1940	John J. Duffy	59	Kings-County, New York	Ireland	Bartender	Head
1920	John Duffy		Hudson, New Jersey	Ireland	Electrician	Head
1920	John Duffy		Luzerne, Pennsylvania	Ireland	Miner	Head
1940	John Duffy	50	Queens-County, New York	Ireland	Motorman	Head
1940	John J. Duffy	53	Allegheny-County, Pennsylvania	Scotland	Foreman	Head
1920	John Duffy		New York, New York	Ireland	—	Head
1940	John Duffy	65	Suffolk-County, Massachusetts	Ireland	Watchman	Head
1940	John H Duffy	66	Bristol-County, Massachusetts	New Jersey	Weaver	Head
1910	John Duffy		Orleans, Louisiana	Louisiana	Gardner	Head
1930	John Duffy		Essex, New Jersey	Ireland	—	Head
1930	John Duffy		Nicholas, West Virginia	West Virginia	Farm Laborer	Son
1920	John Duffy		New York, New York	New York	—	Son
1920	John V Duffy		Cook, Illinois	Illinois	None	Son
1930	John Duffy		Providence, Rhode Island	Rhode Island	Laborer	Son
1910	John F. Duffy		Flathead, Montana	Ohio	Lawyer	Head
1920	John E. Duffy		Philadelphia, Pennsylvania	Pennsylvania	Clerk	Son
1940	John Duffy	21	Hudson-County, New Jersey	New Jersey	Gas Station Attendant	Son
1910	John J Duffy		Middlesex, Massachusetts	Massachusetts	None	Son
1930	John Jr. Duffy		Worcester, Massachusetts	Massachusetts	—	Son
1910	John J Duffy		Providence, Rhode Island	Rhode Island	Doffer	Son

Load More John Duffy Census Records

About John Duffy US Census Records & Model Tree

We've indexed 8460 free, proprietary US Census records for John Duffy 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 8460 US Census records for John Duffy, 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 Duffy'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 Duffy 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 Duffy 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.

Other Duffy US Census Records

Edward Duffy James Duffy Margaret Duffy Mary Duffy Thomas Duffy William Duffy

All Duffy census records →

Browse More Surnames

Douglas Downey Doyle Drake Driscoll Dudley Dugan Duggan Duke Duncan Dunlap Dunn

← Back to US Census Records