Germany Historical Geography
A good historical atlas with chronological overview maps beginning in the early 19th Century and short descriptive explanations of each time petriod (in English) is found here.
A good tool for understanding the political divisions of the later German Empire is this set of maps showing each German state or kingdom in 1789 found at http://www.hoeckmann.de/germany/index.htm .
Online German historical Atlases F. W. Putzgers Historischer Schul-Atlas, 1905 is in many ways as useful for showing the various regions, states, and political divisions of area covered by the German Empire. Some maps from the 1912 edition are also available online. This atlas is in German.
Printed Historical Atlases
Several good historical atlasses showing progressive boundary changes within the area that becomes the Emire of Germany, with accompanying explanations are available in print. They are written in German.
Kleiner Atlas zur deutschen Territorialgeschichte Authors: Bernhart Jähnig; Ludwig Biewer Publisher: Bonn : Kulturstiftung der Deutschen Vertriebenen, 1991. Edition/Format: Map : Atlas : German : 2., erw. AuflView all editions and formats ISBN: 3885570963 9783885570967 OCLC Number: 25075122
Grosser Atlas zur Weltgeschichte Author: Joachim Dornbusch; Ekkehard Aner; et al Publisher: Braunschweig : Westermann, 1997. ISBN: 3075095206 9783075095201 OCLC Number: 40326798 FHL Call # INTL 940 E7wg 2001