Post-1918 Poland according to American experts

[Peterski]

These are the borders of post-WW1 Poland as proposed by The Inquiry, a group of 150 American experts summoned by President Wilson:

https://en.wikipedia.org/wiki/The_Inquiry

A group of Inquiry members at the Paris Peace Conference in 1919:

https://upload.wikimedia.org/wikipedia/commons/8/87/Inquiry_members_at_the_Paris_Peace_Conference_1919 .jpg

Map:

http://www.lithuanianmaps.com/images/1918_Proposed_frontiers_of_Poland_WWilson_papersma pywig_COMP.jpg

http://www.lithuanianmaps.com/images/1918_Proposed_frontiers_of_Poland_WWilson_papersma pywig_COMP.jpg

There was also Jules Cambon's Commission which suggested very similar borders as The Inquiry, but slightly less favourable for Poland:

https://www.britannica.com/biography/Jules-Cambon

"During the Versailles peace conferences, he served as chairman of the commissions for Greek, Czech, and Polish matters."

Check also:

https://www.theapricity.com/forum/showthread.php?241851-Population-of-present-day-Poland-ca-1900