Today’s mini-lesson is on using historical maps on Google Earth. Google Earth should be installed, but you also need a digital image of a map. If you don’t have any map images, check my Maps and Land Records page either by clicking the live link or by going to the home page and choosing “Resource Toolbox” and scrolling down to Maps and Land Records. The David Rumsey Map Collection is a good place to search first. If you have an exact address where someone lived, choose that town first and see if there is a plat map that shows landowners that includes your family’s name.
You can also do an Advanced Google search and put in “plat map” along with the place name and see what hits you get.
I have a book titled Atlas of Washington County, Maine, Compiled, drawn and Published from Official Plans and Actual Surveys by George N. Colby & Co., Houlton and Machias, ME 1881. In it is a map showing Calais, Maine and environs. My 3x great grandfather, Thomas Coleman, is one of the names on the map and the location of his property is marked. I am going to use this map as an example and I scanned part of the page, saving it as a jpg.
1. When you have a digital map image saved, open Google Earth and fly to that place. I flew to Calais, Maine:
Calais, Maine on Google Earth
Calais sits right on the St. Croix River, which borders New Brunswick, Canada. That is why this map has the yellow line zigzagging through it.
2. Next, look at the top menu bar on Google Earth and click “Image Overlay.” It is the 4th icon from the left, not counting the blue “Hide Sidebar” icon. A new image overlay box will open on your screen:
New Overlay Image Box
3. Name your image and, if you like, write a short description about it and/or the source. I included the book citation and the fact that it is Thomas Coleman’s land because I have many other family members who lived in Calais. NOTE: After you open your image following the directions below, DO NOT click “OK” at the bottom of the box yet.
Map Source and Description
Notice that the link box is still empty. There is a BROWSE button to the right of the Link box. Click on BROWSE to find the map image on your computer and click to open. DO NOT click “OK” at the bottom of the box, as we are not yet finished.
Your screen should look something like this:
Map Image Plus Overlay Description Box
4. Notice that in the gray box, below Link location box, there is a Transparency slider that ranges from CLEAR to OPAQUE. Right now, it is all the way over towards OPAQUE, as far as it will go.
Move your mouse onto the top of the gray box and drag it over to the left so you can see all or most of your map.
Box Moved to Left Side of Screen
If you prefer, you can also close your sidebar so that the map fills the screen. I like keeping mine open.
5. Next, move the Transparency slider in the gray box to the left. Play with it a bit to see how clear or how opaque you can make your map. You are going to manipulate your map so that your image lays correctly on top of the Google Earth map. I find that the transparency slider is best set about 25% across the bar so I can see enough of my own image to try to match it to Google Earth.
Transparency Slider Set About 25% of Way
Across the Bar
There should be a green cross centered over your town. Mine is over downtown Calais.
6. Now it is time to match up streets, waterways, major highways, geographic points or whatever major points are found on your individual map. Because Calais sits on the St. Croix River and Red Beach goes down the Atlantic Ocean coast, I am going to use the curves of the land and waterways to align my image on top of the Google Earth map.
Touch your cursor to the middle of the green X to move your entire map image north, south, east or west. On the left side of the image, there is a diamond shape. Once you have the whole map set where you want it, put your cursor in the diamond box to rotate the map. You can move back and forth between the X and the diamond to adjust your map until you have it lined up as well as you can.
Some maps will match Google Earth exactly because they were surveyed correctly to scale. The map I am using of Calais is approximate, as you can see that the actual coastline doesn’t entirely match up to Mr. Colby’s drawing. This is about as close as I can get the maps to match up:
Aligned Image and Google Earth
If you are using a city plat map, you will be able to align the streets exactly. I used the Transparency slider bar to make my image more opaque. I also added the red arrow to point out “T. Coleman.”
T. Coleman Land – Red Arrow
This is important to me because Thomas died in 1888, wife Mary in 1889 and son William inherited the property. William died in 1905, but his wife, Sarah, survived until 1930. One of their sons, my great grandfather, Hartwell T. Coleman, ran a small store and gas station near the family home in Red Beach until the 1930’s. I even have a photo of the store, which I will use in another post.
From this map, I can see right where Thomas’s land is and the approximate distance from modern day Calais.
7. Now to SAVE the overlay. When the overlay is aligned the way you want it, click the OK in the gray image description and link box.
Go up to the Google Earth menu bar and click on FILE. Choose SAVE and SAVE AS. Save your file to the place of your choice on your computer. It will save as a KMZ file, which is the format that Google Earth uses.
8. What if you don’t want to see your map all the time? Easy! Look at your Places box on the left side of the screen. The file you’ve created and named – for me, it’s “ThomasColemanCalaisME” is highlighted in blue.
There is a small box to the left that is checked. If you only want to see the Google Earth map, just uncheck the box and your overlay will disappear. Check the box and the overlay will reappear.
Tomorrow, I will explain how to add an image to your Google Earth map.