Michigan Plat Maps: What They Show and Where to Find Them

What is a plat map, and how is it different from a regular map?

A plat map is a drawing of land ownership, not a drawing of a place. Where an ordinary map shows roads, towns, and rivers, a plat — sometimes called a cadastral map — shows how the underlying land was divided into individually owned lots and parcels, with each owner’s name written directly on their piece of ground. County plat books stacked these maps together, township by township, so a single volume could cover an entire county’s landowners at a glance.

Most of Michigan’s surviving plat books date from the 1870s through the 1930s, the era when commercial map publishers went county by county producing land ownership atlases for sale to the farmers and townspeople who appeared on them. A later map might show a parcel labeled with a subdivision name; an 1890s plat book will show it labeled with a person’s name. Modern GIS parcel-viewer sites do the same job for today’s property lines and current assessor data, but they start where the historical plat book ends — most only go back a few decades, not a century or more.

Why are plat maps such a valuable genealogy source?

Because they answer a question a deed alone often can’t: who lived next door. A plat map puts your ancestor’s name on a specific 40, 80, or 160-acre parcel in a specific year, and it puts everyone else’s name on the parcels around it at the same moment. In rural Michigan, families frequently bought adjoining or nearby land on purpose — a father and married son, in-laws, or siblings homesteading near each other — so the neighboring names on a plat map are often relatives you haven’t identified yet through any other record.

I’ve used a plat map to break through more than one dead end this way: a maiden name that never showed up in an index turned out to belong to the family farming the next parcel over. The map doesn’t prove a relationship by itself, but it tells you exactly whose deeds, probate files, and church records to check next.

Where can I find historical Michigan plat maps?

Several institutions hold Michigan’s plat books and land ownership atlases, and each has different strengths:

The Library of Congress collection alone covers dozens of Michigan counties — Kalamazoo, Mecosta, Wayne, Ogemaw, Hillsdale, Benzie, and more — each digitized page by page and free to browse without an account. The University of Michigan’s county histories collection is a good second stop when the Library of Congress doesn’t have the specific county or year you need.

How do I read and use a Michigan plat map for research?

1. Find the township and range. Michigan land descriptions use the Public Land Survey System grid of townships and ranges, and knowing your ancestor’s numbers lets you go straight to the right page instead of paging through an entire county atlas.
2. Locate the right year. Plat books were reissued periodically, so a parcel’s owner can change between editions — pull more than one year if you’re tracking when land changed hands.
3. Read the parcel and note the acreage. Most plats mark each parcel’s size, which helps confirm you’ve got the right piece of land when cross-checking against a deed.
4. Note the neighboring names. Write down who owned the surrounding parcels; shared surnames or names that reappear across multiple maps are worth chasing separately.
5. Cross-reference with deed and tax records. A county’s register of deeds holds the paper trail — sale price, prior owner, and legal description — that a plat map only summarizes visually.

What about towns that disappeared or changed names?

Michigan has dozens of platted villages that never grew past a mill, a store, and a post office, and plat maps are often the only visual record that they existed at all. Kensington, in Oakland County, was platted in 1836, briefly had a post office and a few hundred residents, and faded once the railroad and later highway construction bypassed it — by the 1950s it was gone entirely. Salt River, in Isabella County, was platted in 1866 around a set of mills, then was absorbed into the growing town of Shepherd by 1889 and stopped appearing as a separate place on later maps.

If a family history mentions a Michigan place name you can’t find on a modern map, check an older plat map or county atlas from the right decade before assuming the name was recorded wrong — it may simply be a village that didn’t survive.

Frequently asked questions

What’s the difference between a plat map and a regular map? A regular map shows roads, towns, and terrain. A plat map is a cadastral map — it shows how the land itself was divided into surveyed lots and parcels, with the owner’s name written on each one at the time the map was made.

Where can I find historical Michigan plat maps for free? The Library of Congress has digitized dozens of Michigan county atlases and plat books published before 1922, freely viewable online. The University of Michigan’s Michigan County Histories and Atlases collection covers hundreds more county histories and atlases published before 1923, also free and keyword-searchable.

Why do plat maps matter for genealogy research? They put your ancestor’s name on a specific piece of ground in a specific year and show exactly who farmed the land around them. Rural Michigan families often settled in clusters, so the names on the parcels next door are frequently relatives — a clue that a deed record alone won’t hand you.

What happened to Michigan towns that don’t exist anymore? Most disappeared for ordinary reasons — a railroad routed around them, a post office closed, or a bigger neighboring town absorbed them. Kensington in Oakland County and Salt River in Isabella County are two examples: both were platted villages that show up on 19th-century maps and vanished from later ones.

Do I need to know the township and range to search a plat map? It helps a great deal. Michigan land is described using the Public Land Survey System’s township and range grid, and knowing those numbers for your ancestor’s parcel lets you go straight to the right page of a plat book instead of scanning an entire county.