The divided house referred to in this speech was caused primarily by

This speech was caused by slavery.

Abe Lincoln, who gives this famous speech, essentially says that that United States won't be able to exist as half free and half slave. He believes that the nation will allow slavery completely or it will get rid of it completely. This speech is extremely significant because Lincoln is predicting the eventual Civil War. This speech was given in 1858, 3 years before the Civil War started.