The answer is racial discrimination.
Jim Crow Laws were laws created to segregate the White and
Black Americans in the mid-19th century. These laws were created by
the Democratic party wherein they have given the Black Americans equal rights
but they have created their own public facilities to separate them from the
White Americans.
During the Japanese invasion of the Manchuria, President Hoover outlined the Hoover-Stimson Doctrine—a note that was supposed to be a message to Japan and China, contains the policy of non-recognition of any international territories that was gained by brutal force.
I believe it was the New Jersey Plan, which proposed that "e<span>ach state was equal regardless of the size of its population."</span>