The Wonders of Plat Maps

“This is such a beautiful building. What used to be in it?” “How old is my house?” “Where was the Lyceum Theater?” “I’ve never heard of that street. Does it still exist?” We get questions like these in Local History all the time. Many of these questions can be answered by using the Rochester City Directory or the suburban directories in our collections. In many cases, however, just knowing a street address or even on what corner a building stood might not tell you enough. You need a visual—some kind of map, maybe—to help you with your question. An old street map is great, but still doesn’t show you the kind of detail you might need. So what do you do? Find a plat map. Plat maps for the City of Rochester were done every 8-15 years from 1875 through 1935. Monroe County plat maps were issued less frequently, but some towns continued to produce them into the 1960s. These maps were issued in very large books. Some pages are three feet long, and the book may have dozens of pages, making them very costly to produce.

Plat maps show ownership or occupancy right on the map. Many of our early area maps and the earlier plat maps show exactly who owned every piece of land in a town or the city. As we move forward in time, the city plat maps give even more detail. Take a look at part of a page from the 1910 Hopkins Atlas of the City of Rochester. Rochester was a very busy, hopping place, with many things to do. The intersection of Main Street (center) and Clinton Avenue was busy with a four-way streetcar interchange. Sibley’s and McCurdy’s stores flanked Main Street, while many hotels, such as the Whitcomb House and the Hotel Seneca, took up substantial real estate. Large movie theaters, such as the Temple and Lyceum, were just down Clinton Avenue.

Rochester Plat 1910 downtown plate 2 excerpt

Just southwest of this view, on the same map, the Erie Canal Aqueduct crosses the Genesee River. The Osburn House, Genesee Amusement, and the YMCA sit on the east side of South Avenue, where the Bausch & Lomb building of the library and parking ramp are now.  In 1910, there were no buildings where the library’s Rundel Building now stands, only an overlook to the Erie Canal, the Johnson and Seymour Mill Race, and the Genesee River.


The 1905 photo below shows the view looking northward on South Avenue. The large building with the arched façade is Genesee Amusement; the two towers belong to the Osburn House, and the building in the distance is the Granite Building, original home of Sibley’s Department Store, which still stands today. Note the streetcar wires suspended in the air.


Plat maps give many other details, such as lot size, tract name, house numbers (very important as most street numbers changed around the turn of the 20th century), and are even color-coded as to what material a building is made of—wood frame, stone, or brick. Each house is shown in its exact shape and placement on the lot, making it easier to recognize individual buildings. Other details regarding utilities and industrial facilities may also appear on the maps.

People often ask about the age of their home. The Monroe County tax rolls or City assessment cards can provide that information, but for older homes, it is not always right. Many homes built prior to 1920 have only approximate or default dates. The plat maps can show the presence of a house prior to that published date. Using the maps, along with directories, may help to narrow down the exact age of a building. Street name and house number changes can be visually verified.

Plat maps can also be used to discover information in a photograph. We have been able to use plat maps to help ascertain the location of a photograph, based on clues in the picture, and the angle from which it was taken. We’ve identified churches and office buildings in photos based on the vantage point and other landmarks.

“So how do I see these maps?” Come on down to the Local History and Genealogy Division of the library to see them in person, which is really the best way to make use of them. Or, you can see them on the library’s website:

The individual links (click on the year) connect to maps that accompanied City or other directories; the links labeled “Plat Book” or “Atlas” connect to a search for each individual book of plat maps. From the list, select a map to view or read a description about the area covered.

No matter what your reason for consulting these maps, you will enjoy them. Happy researching!

Gabriel Pellegrino

Published in: on February 1, 2013 at 5:53 pm  Comments (1)  

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One CommentLeave a comment

  1. I could pore over plat maps all day. One of the many fascinating treasures found in the Rochester Local History and Genealogy division!

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