File:Germany and Poland borders during the 20th century.gif

Summary
Anachronical map of Germany and Poland border changes during the 20th century.

The borders represent:

Until World War I:


 * Congress Poland
 * German Empire

After World War I until Anschluss:


 * Weimar Republic
 * Second Polish Republic
 * Free City of Danzig

After World War II until the Revolutions of 1989:


 * People's Republic of Poland
 * West Berlin
 * West Germany
 * East Germany

After the end of the Soviet Union:


 * Poland
 * Germany
 * Lithuania
 * Ukraine
 * Belarus

I made this map on a Beige G3 running Photoshop using these maps as reference:


 * KingdomofPoland1815.jpg
 * Österreich-Ungarns Ende.png
 * Germanborders.svg
 * Curzon line en.svg

Other versions
A flag-coloured one… is here, at Wikimedia Commons.