I knew my Rohrer family was from Ellwangen, Germany, so I was curious to see where the current Rohrers were located. The map below shows the relative distribution for the Rohrer surname based on number of entries per million. The darker the color, the more Rohers are located in that area.
Ellwangen is in the district of Ostalbkreis, which I've circled on the image below. Interesting to see that my Rohers were from the same part of Germany where many of the present day Rohers are concentrated.
The site also has some other tools. A Name Graph shows similar surnames. This seems to be random since I get a different set of names each time I select it, but it does point out some different spellings to try. There is also an option for an absolute distribution map which is color coded based strictly on the number of entries for an area. The relative and absolute maps were fairly similar for the Rohrer families. A pie chart tool displays the surname distribution sorted by Federal States.
The Geogen site was developed by Christoph Stöpel and is free to use. Images may be posted as long as they are not commercial and the copyright notice is not removed. Thanks to Family Tree Magazine for mentioning Geogen on their Facebook page.
Mappy Monday is a GeneaBloggers prompt where you can post map images and how they relate to your research or discuss other aspects of land ownership and your ancestor.