William Duffy — US Census Records & Model Tree
We found 3929 free census records for William Duffy across 6 census years (1900–1950), in 48 states, DC, and 1 territory and 561 counties. Each record includes our Model Tree — the same person linked across decades using machine learning, with per-link confidence scores.
William Duffy Census Records by State & County
Census Record Search
| Year | Name | Age | Location | Birthplace | Occupation | Relation |
|---|---|---|---|---|---|---|
| 1940 | William Duffy | 20 | Worcester-County, Massachusetts | Massachusetts | Room Worker | Son |
| 1920 | William Duffy | New York, New York | New York | — | Son | |
| 1940 | William Duffy | 24 | Jefferson-County, Kentucky | Kentucky | Bookkeeper | Son |
| 1900 | William Duffy | 41 | Phila, Pennsylvania | Ireland | Upholsterer | Head |
| 1920 | William H. Duffy | Philadelphia, Pennsylvania | Ireland | — | Head | |
| 1910 | William Duffy | Hudson, New Jersey | New York | — | Son | |
| 1930 | William Duffy | Hudson, New Jersey | New Jersey | — | Son | |
| 1930 | William Duffy | New York, New York | New York | None | Son | |
| 1920 | William P. Duffy | Iowa, Iowa | Iowa | Farm Laborer | Son | |
| 1930 | William Duffy | New York, New York | New York | — | Son | |
| 1940 | William Jr. Duffy | 21 | Allamakee-County, Iowa | Iowa | Farm Labor | Son |
| 1930 | William Duffy | Cook, Illinois | Illinois | — | Son | |
| 1930 | William Jr Duffy | Suffolk, Massachusetts | Massachusetts | — | Son | |
| 1940 | William Duffy | 18 | Blair-County, Pennsylvania | Pennsylvania | — | Son |
| 1930 | William Duffy | Suffolk, Massachusetts | Massachusetts | Steamfitter | Head | |
| 1910 | William Duffy | Passaic, New Jersey | New Jersey | Warper | Son | |
| 1910 | William Duffy | Westchester, New York | New York | — | Head | |
| 1930 | William H. Duffy | Essex, New Jersey | New Jersey | Chauffeur | Son | |
| 1940 | William Duffy | 17 | Richmond-County, New York | New York | — | Son |
| 1910 | William Duffy | Northumberland, Pennsylvania | Pennsylvania | Laborer | Son | |
| 1930 | William Duffy | Queens, New York | New York | None | Son | |
| 1920 | William H Duffy | Butler, Pennsylvania | Pennsylvania | Farmer | Head | |
| 1920 | William H. Jr. Duffy | Erie, Pennsylvania | Pennsylvania | None | Son | |
| 1940 | William Duffy | 23 | Cook-County, Illinois | Illinois | Shipping Clerk | Son |
| 1910 | William Duffy | Strafford, New Hampshire | New Hampshire | — | Son | |
| 1940 | William Duffy | 20 | Allegheny-County, Pennsylvania | Pennsylvania | Laborer | Son |
| 1910 | William J. Duffy | Bristol, Massachusetts | Massachusetts | None | Son | |
| 1900 | William O Duffy | Shawnee, Kansas | Kansas | — | Son | |
| 1940 | William Duffy | 12 | Kings-County, New York | New York | — | Son |
| 1940 | William Duffy | 17 | Hudson-County, New Jersey | New Jersey | — | Son |
About William Duffy US Census Records & Model Tree
We've indexed 3929 free, proprietary US Census records for William Duffy across 1900–1950, covering 48 states, DC, and 1 territory: Alabama, American Samoa, 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 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.
Last updated: July 30, 2026
Frequently Asked Questions
- We have 3929 US Census records for William Duffy, from 1900 to 1950, across 48 states, DC, and 1 territory.
- 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 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 William 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 William Duffy records from the 1900 through 1950 US Federal Census, across 48 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.