How many Mary Koch census records do you have?

We have 3221 US Census records for Mary Koch, from 1900 to 1950, across 44 states and DC.

What's in a Mary Koch census record?

You'll see Mary'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 Mary Koch'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 Mary Koch census records free?

Yes. All Mary Koch 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 Mary Koch?

We have Mary Koch records from the 1900 through 1950 US Federal Census, across 44 states and DC. Use the year and state filters to narrow your results.

How do I find Mary Koch 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 Mary Koch?

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.

Mary Koch — US Census Records & Model Tree

We found 3221 free census records for Mary Koch across 6 census years (1900–1950), in 44 states and DC and 579 counties. Each record includes our Model Tree — the same person linked across decades using machine learning, with per-link confidence scores.

Mary Koch Census Records by State & County

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Showing of 3221 records for Mary Koch US Census, ranked by Model Tree richness

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Year	Name	Age	Location	Birthplace	Occupation	Relation
1930	Mary Koch		Cook, Illinois	Germany	—	Wife
1910	Mary Koch		Ramsey, Minnesota	Germany	None	Head
1940	Mary Koch	64	Cook-County, Illinois	Germany	—	Head
1920	Mary Koch		Sangamon, Illinois	Germany	None	Head
1940	Mary Koch	43	Logan-County, Arkansas	Arkansas	—	Wife
1900	Mary Koch	48	Philadelphia, Pennsylvania	Germany	—	Wife
1910	Mary Koch		San Francisco, California	Germany	—	Wife
1910	Mary Koch		Los Angeles, California	Germany	—	Daughter
1940	Mary Koch	14	Livingston-County, Michigan	Michigan	—	Daughter
1910	Mary Koch		Sarpy, Nebraska	Nebraska	—	Wife
1920	Mary S. Koch		Allegheny, Pennsylvania	Germany	None	Wife
1900	Mary Koch	10	Kittitas, Washington	Washington	—	Daughter
1940	Mary L. Koch	38	Jefferson-County, Kentucky	Kentucky	—	Wife
1930	Mary M Koch		King, Washington	Washington	—	Daughter
1940	Mary Koch	55	Morton-County, North Dakota	Hungary	—	Wife
1940	Mary Koch	24	Marion-County, Kansas	Nebraska	Housekeeper	Daughter
1940	Mary A Koch	45	Lincoln-County, Nebraska	Nebraska	House Work	Head
1940	Mary Lou Koch	12	Dane-County, Wisconsin	Wisconsin	—	Daughter
1920	Mary Koch		Queens, New York	Germany	None	Wife
1930	Mary Koch		Ellis, Oklahoma	Russia	—	Wife
1930	Mary M Koch		San Diego, California	California	None	Wife
1910	Mary Koch		Kings, New York	Germany	—	Wife
1940	Mary Koch	43	Onondaga-County, New York	Czechoslovakia	Helper	Wife
1940	Mary Ann Koch	14	Cook-County, Illinois	Illinois	—	Daughter
1940	Mary Koch	41	Scotts-Bluff-County, Nebraska	Russia	Housework	Wife
1940	Mary Koch	79	Cloud-County, Kansas	Germany	—	Head
1910	Mary Koch		Grant, South Dakota	Minnesota	—	Wife
1930	Mary E Koch		Hennepin, Minnesota	Minnesota	None	Daughter
1940	Mary Koch	30	Logan-County, Arkansas	Arkansas	—	Wife
1940	Mary Koch	26	Marion-County, Kansas	Kansas	House Keeper	Daughter

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About Mary Koch US Census Records & Model Tree

We've indexed 3221 free, proprietary US Census records for Mary Koch across 1900–1950, covering 44 states and DC: Alabama, Alaska, Arizona, Arkansas, California, Colorado, Connecticut, District of Columbia, Florida, Georgia, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Maryland, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, New Jersey, New Mexico, New York, North Carolina, North Dakota, Ohio, Oklahoma, Oregon, Pennsylvania, Rhode Island, South Dakota, Tennessee, Texas, Utah, 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 Mary 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 3221 US Census records for Mary Koch, from 1900 to 1950, across 44 states and DC.
: You'll see Mary'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 Mary Koch'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 Mary Koch 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 Mary Koch records from the 1900 through 1950 US Federal Census, across 44 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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